From Newsgroup: alt.os.linux.mint

I connected a brand new Asus Tuf 850W PSU to an ASUS motherboard with
just the processor and heatsink installed, in a MIDI Tower case.

The PSU was not in the case.

Switched on and...

Nothing happened.

I detached the PSU and attached a small tester to it.
Powered on ...

No sign of life.

What can cause a PSU to die under those conditions?
Surely it has inbuilt protection against overload.




--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: alt.os.linux.mint

On 2025-07-16, pinnerite wrote:

I connected a brand new Asus Tuf 850W PSU to an ASUS motherboard with
just the processor and heatsink installed, in a MIDI Tower case.

The PSU was not in the case.

Switched on and...

Nothing happened.

Is the PSU power switch "on"?
Is the plug securely connected at both ends?
Wall socket is switched on (if switched, those ones always trip me up).
--
|_|O|_|
|_|_|O| Github: https://github.com/dpurgert
|O|O|O| PGP: DDAB 23FB 19FA 7D85 1CC1 E067 6D65 70E5 4CE7 2860
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From Newsgroup: alt.os.linux.mint

pinnerite wrote:

Switched on and...

Did the PS fan /budge/?

My first suspicion is not a dead new PS, but something 'incomplete' in
your 'circuitry' related to the mobo's connectivity.
--
Mike Easter
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: alt.os.linux.mint

On Wed, 7/16/2025 10:50 AM, pinnerite wrote:

I connected a brand new Asus Tuf 850W PSU to an ASUS motherboard with
just the processor and heatsink installed, in a MIDI Tower case.

The PSU was not in the case.

Switched on and...

Nothing happened.

I detached the PSU and attached a small tester to it.
Powered on ...

No sign of life.

What can cause a PSU to die under those conditions?
Surely it has inbuilt protection against overload.

Review here. Fan only comes on with more than 220W loading on output.

https://www.tomshardware.com/pc-components/power-supplies/asus-tuf-gaming-850w-gold-power-supply-review

"The OEM behind the creation of the TUF Gaming 850W Gold PSU is Great Wall, a Chinese OEM
that became known in the Western markets only a few years back when Corsair decided to use
them for several of their mainstream products."

This is similar to how a lot of PSU get made. Like Antec using ChannelWell for at least
half their designs, and maybe Delta for a few. As a buyer, you have to track down this
info, and check whether the OEM has a "seedy history". Some OEMs in the old days, just
could not help but put leaky caps in their products (I have some leaky caps in the junk room).

*******

To start the unit, you need to ground PS_ON# on the main 24 pin cable.
Your tester cable should have a switch for this purpose.

The main 24 pin cable on your modular supply has two connectors on the end. Both must be plugged in, and both of the connectors are next to one another. There are more than 24 pins on the PSU side cabling and the two connectors. This allows things like remote sense wires, to have their own pins on the
PSU side. Make sure both cables are thoroughly seated on the PSU side,
then try your PSU switch again on the load side.

Your tester should also have a small test load, five to ten watts,
to encourage the unit to work. Some PSUs have their own small test load
inside, for the same purpose, namely drawing some energy from reactive
circuits to keep the output "under loop control". In order for a PSU
to achieve an "I work at zero load" rating, some of them must load a
rail internally, to keep the feedback loop working.

ATX PSUs, the switchers "push" but do not "pull" to regulate the output.
This means, when the voltage drops... the ATX pushes harder. Now,
say that nobody were to draw any current at all. Even the internal load disconnected.

If that happened, the output would rise above nominal (the PSU would be pushing but nothing would be pulling to keep the voltage under control). Maybe the 12V would rise
to 13V, and that is not a lucky number. The OVP would cut in, and shut off the supply.
An activity like this, may not share precisely the time constant mentioned
in the next section. The OVP should work instantly, to help protect
sensitive semiconductors on the motherboard.

*******

As the participants have already mentioned, check for an ATX case fan which is "twitching" when you apply power. For test purposes while the ATX PSU is out of the computer case, you can use one of your Molex 1x4 fitted fans as a test article,
connect to a Molex output, now try to ground PS_ON#, look for a "twitch" on the fan blade.

The PSU has OCP which only starts to check for overcurrent, at the 35 millisecond mark.
For the first 35 milliseconds, the PSU can provide as much current as it wants (well
above the 850W level), and the PSU does not care. This interval is used to charge up
all the output caps on the secondary side. Past the 35 millisecond mark, the PSU is
more attentive to overload. Each major loom for example, might be equipped with 12V @ 20A sensing. You cannot draw the entire 70A rating of the supply, through any
single loom. While the 12VHPWR may seem to support 600W (12V @ 50A), this may have
been split into two looms. If the load is imbalanced across the yellow wires, the PSU will cut out, even though exactly 600W was not being delivered at the time.
Having limits like this, is to avoid silly accidents.

The supply has a status signal "PWR_OK" which is active high and is 5V logic. PWR_OK waits until the capacitors are almost charged up. Maybe the
12V rail is 11.5V when the PWR_OK is asserted. The motherboard will
not come out of RESET, until PWR_OK signals the rails are stable,
and onboard regulators also indicate that their rails are stable, and
then the first instruction can be executed.

*******

Summary: Power supplies can be DOA. With an OEM, Great Wall tests the unit and puts it
in the box. They have professional PSU testers and automation, to run the
unit up to full power, check tolerances and so on.

Asus does not 100% retest the units before shipping the 40 foot
containers. Only statistical sampling is used (to check that the boxes are
not full of rocks or something). It's quite easy for a brand new PSU to be
DOA. It's not a strong endorsement for the "hosting company" like Asus -- some
manufacturers are very good about not delivering DOA units.

This is one reason my PSU purchases have been at local stores, I can
drive back and swap for another. After the tech in the repair section,
double-checks my test result (like when my new HDD would not spin the platter).

The twitching behavior would be a sign of life, and would prove the
mains cable was fully seated, and for non-autoswitcher supplies, the
selector switch is fully in the 240V position. There can still be
supplies out there, that need the switch set correctly, and you could
blow the shit out of something if your PSU has that and you did not
set it correctly.

Paul
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: alt.os.linux.mint

On 7/16/25 16:50, pinnerite wrote:

I connected a brand new Asus Tuf 850W PSU to an ASUS motherboard with
just the processor and heatsink installed, in a MIDI Tower case.

The PSU was not in the case.

Switched on and...

Nothing happened.

I detached the PSU and attached a small tester to it.
Powered on ...

No sign of life.

What can cause a PSU to die under those conditions?
Surely it has inbuilt protection against overload.

What comes to mind is, it didn't die but doesn't switch on.
There might be a electrical check that isn't happy.
Are you sure you connected all plugs and cables to the mainboard?

As usual, if everything else fails, read the manual.
--
-------------

Godspeed for Assange
Amnesty for Snowden
Rehabilitation for heroes

Edmund
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: alt.os.linux.mint

Edmund wrote:

On 7/16/25 16:50, pinnerite wrote:

I connected a brand new Asus Tuf 850W PSU to an ASUS motherboard with
just the processor and heatsink installed, in a MIDI Tower case.

The PSU was not in the case.

Switched on and...

Nothing happened.

I detached the PSU and attached a small tester to it.
Powered on ...

No sign of life.

What can cause a PSU to die under those conditions?
Surely it has inbuilt protection against overload.

What comes to mind is, it didn't die but doesn't switch on.
There might be a electrical check that isn't happy.
Are you sure you connected all plugs and cables to the mainboard?

As usual, if everything else fails, read the manual.

also did he connect the CPU 12v power, and the case switch cable to motherboard power switch pins?
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: alt.os.linux.mint

On 7/18/25 15:16, Felix wrote:

Edmund wrote:

On 7/16/25 16:50, pinnerite wrote:

I connected a brand new Asus Tuf 850W PSU to an ASUS motherboard with
just the processor and heatsink installed, in a MIDI Tower case.

The PSU was not in the case.

Switched on and...

Nothing happened.

I detached the PSU and attached a small tester to it.
Powered on ...

No sign of life.

What can cause a PSU to die under those conditions?
Surely it has inbuilt protection against overload.

What comes to mind is, it didn't die but doesn't switch on.
There might be a electrical check that isn't happy.
Are you sure you connected all plugs and cables to the mainboard?

As usual, if everything else fails, read the manual.

also did he connect the CPU 12v power, and the case switch cable to motherboard power switch pins?

Exactly
--
-------------

Godspeed for Assange
Amnesty for Snowden
Rehabilitation for heroes

Edmund
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: alt.os.linux.mint

On Fri, 7/18/2025 3:29 AM, Edmund wrote:

On 7/16/25 16:50, pinnerite wrote:

I connected a brand new Asus Tuf 850W PSU to an ASUS motherboard with
just the processor and heatsink installed, in a MIDI Tower case.

The PSU was not in the case.

Switched on and...

Nothing happened.

I detached the PSU and attached a small tester to it.
Powered on ...

No sign of life.

What can cause a PSU to die under those conditions?
Surely it has inbuilt protection against overload.

What comes to mind is, it didn't die but doesn't switch on.
There might be a electrical check that isn't happy.
Are you sure you connected all plugs and cables to the mainboard?

As usual, if everything else fails, read the manual.

ATX PSU are pretty simple.

1) Switch on at back.
Check the +5VSB pin for 5V output. The PSU cannot
start, unless 5V is present on the +5VSB pin.

When sitting idle like that, and without Alans PSU tester
plugged in, the +5VSB pin and the PS_ON# pin should both have
the same five volt voltage on them.

2) Ground the PS_ON# pin. This turns on the main rails
3.3V, 5V, 12V. Fans should spin. If a cooling fan only
"twitches", then the PSU is cutting out on overcurrent.
You can connect a couple cooling fans you have fitted
with Molex, to work as "indicator loads" for such a test
outside of the computer case. I have a few fans with
Molex on them.

While the PSU have a slow blow fuse inside the housing,
those almost never trip. You can use your Kill-A-Watt meter,
cable up the PSU, and if absolutely no current at all is
drawn under any circumstances, THEN it could be an open fuse.

While this circuit is not up-to-date with the latest practice
(this circuit does not use double forward conversion), a lot
of the elements in here are still the same. This will help
you understand a bit of the circuit behavior.

http://www.pavouk.org/hw/en_atxps.html

For example, NTCR1 on the left, is the inrush limiter. The PSU
on the computer across from me, has a relay in that circuit.
The relay closes and shorts out NTCR1 so there is no voltage
drop across it, when the PSU is fully charged (inrush charging).
So while the pavouk shows *some* solution for inrush, it might
not be exactly the same as the more sophisticated modern approaches
to inrush limiting. You can use the power factor correction circuit,
for inrush limiting too. (That was a fad for a few years.)

Paul
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: alt.os.linux.mint

On Fri, 7/18/2025 9:16 AM, Felix wrote:

Edmund wrote:

On 7/16/25 16:50, pinnerite wrote:

I connected a brand new Asus Tuf 850W PSU to an ASUS motherboard with
just the processor and heatsink installed, in a MIDI Tower case.

The PSU was not in the case.

Switched on and...

Nothing happened.

I detached the PSU and attached a small tester to it.
Powered on ...

No sign of life.

What can cause a PSU to die under those conditions?
Surely it has inbuilt protection against overload.

What comes to mind is, it didn't die but doesn't switch on.
There might be a electrical check that isn't happy.
Are you sure you connected all plugs and cables to the mainboard?

As usual, if everything else fails, read the manual.

also did he connect the CPU 12v power, and the case switch cable to motherboard power switch pins?

He has built systems before.

He is looking for some encouragement.

1) He had a working system.
2) The power supply in the working system, stopped working.
3) A replacement supply is also not working and is not
responding to PS_ON# testing. He tests the supplies before
inserting them into a computer case. The tester is likely
a window comparator type, which tells you whether all rails
are within acceptable voltage.

These are autoswitching supplies, the OP is in the UK and
the supply would be assuming a 240V input (50Hz).

As is standard for UK people, he would have checked the fuse on the cord
fitted to the supply. The fuse has to be able to withstand
the inrush of the supply, when the supply is switched on at
the back of the unit. The internal safety Slo Blow fuse,
easily withstands the inrush current.

A Kill-A-Watt meter, can be used to detect power draw, as
a "sign of life" from the unit.

Overloading the +5VSB, could shut off that output, but it
might be self-restoring rather than being a latch-off circuit.
Some of the +5VSB supplies use switchers now, and the
little switcher is not power factor corrected, so the
reactive component seems rather high when you measure it.

There is no particular advantage to connecting the PSU to
the motherboard, until the question of whether the supply
actually works is resolved. If the supply is good, it should
be able to pass a test, outside of the computer case. All
it takes, for example, is a PSU tester that operated
PS_ON# properly and has the 24 pin pinout of an ATX when
it measures the voltages.

Paul
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: alt.os.linux.mint

On 2025-07-18, Paul wrote:

[...]
These are autoswitching supplies, the OP is in the UK and
the supply would be assuming a 240V input (50Hz).

Man, I remember the days of tripping over the stupid 115/230V switch on
the back being wrong ...
--
|_|O|_|
|_|_|O| Github: https://github.com/dpurgert
|O|O|O| PGP: DDAB 23FB 19FA 7D85 1CC1 E067 6D65 70E5 4CE7 2860
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: alt.os.linux.mint

On Fri, 18 Jul 2025 12:47:35 -0400
Paul <nospam@needed.invalid> wrote:

On Fri, 7/18/2025 9:16 AM, Felix wrote:

Edmund wrote:

On 7/16/25 16:50, pinnerite wrote:

I connected a brand new Asus Tuf 850W PSU to an ASUS motherboard with
just the processor and heatsink installed, in a MIDI Tower case.

The PSU was not in the case.

Switched on and...

Nothing happened.

I detached the PSU and attached a small tester to it.
Powered on ...

No sign of life.

What can cause a PSU to die under those conditions?
Surely it has inbuilt protection against overload.

What comes to mind is, it didn't die but doesn't switch on.
There might be a electrical check that isn't happy.
Are you sure you connected all plugs and cables to the mainboard?

As usual, if everything else fails, read the manual.

also did he connect the CPU 12v power, and the case switch cable to motherboard power switch pins?

He has built systems before.

He is looking for some encouragement.

1) He had a working system.
2) The power supply in the working system, stopped working.
3) A replacement supply is also not working and is not
responding to PS_ON# testing. He tests the supplies before
inserting them into a computer case. The tester is likely
a window comparator type, which tells you whether all rails
are within acceptable voltage.

These are autoswitching supplies, the OP is in the UK and
the supply would be assuming a 240V input (50Hz).

As is standard for UK people, he would have checked the fuse on the cord fitted to the supply. The fuse has to be able to withstand
the inrush of the supply, when the supply is switched on at
the back of the unit. The internal safety Slo Blow fuse,
easily withstands the inrush current.

A Kill-A-Watt meter, can be used to detect power draw, as
a "sign of life" from the unit.

Overloading the +5VSB, could shut off that output, but it
might be self-restoring rather than being a latch-off circuit.
Some of the +5VSB supplies use switchers now, and the
little switcher is not power factor corrected, so the
reactive component seems rather high when you measure it.

There is no particular advantage to connecting the PSU to
the motherboard, until the question of whether the supply
actually works is resolved. If the supply is good, it should
be able to pass a test, outside of the computer case. All
it takes, for example, is a PSU tester that operated
PS_ON# properly and has the 24 pin pinout of an ATX when
it measures the voltages.

Paul

It seems to me after all this that there must be a short.
ChatGPT told me that wihin the box I should find a glass fuse.
I do have a stock so I went open the case of one not in warranty, only
to find I needed two torx screwdrivers. The bit sets that I have
include sizes that are two big.

Down to B&Q and bought the two smallest sizes. 19 & 12.
Got home to find the 10 was OK but I also needed an 8.
It is coming on a slow boat from China.

Th engineer that I hired to take the strain couldn't do it.
He recommended that I buy another motherboard, with LED diagnostic
lamps. I bought a Gigabyte B650 gaming dubree.

Anyway I have tested a Corsair 850Watt and it came up OK.
I plan to glue fibre washers onto the underside of the motherboard
before I fit it in place.

I hope to assemble the whole thing tomorrow afternoon.

Thanks for trying to help everyone.

Alan
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From Newsgroup: alt.os.linux.mint

pinnerite wrote:

Down to B&Q and bought the two smallest sizes. 19 & 12.
Got home to find the 10 was OK but I also needed an 8.

(Learning some torx) wow; I never knew they went from 1-100. I know your
19 above is a typo for 10.

By design, Torx head screws resist cam out better than Phillips head or slot head screws.

I don't have many either, my smallest is a 10, largest 25. I do recall running into a security torx problem in the past, and now I find there
are 'variations'. - paralobe, plus.

There are also a couple of little square Robertsons in my bit set of torx.
--
Mike Easter
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: alt.os.linux.mint

On Mon, 21 Jul 2025 12:50:57 -0700
Mike Easter <MikeE@ster.invalid> wrote:

pinnerite wrote:

Down to B&Q and bought the two smallest sizes. 19 & 12.
Got home to find the 10 was OK but I also needed an 8.

(Learning some torx) wow; I never knew they went from 1-100. I know your
19 above is a typo for 10.

By design, Torx head screws resist cam out better than Phillips head or slot head screws.

I don't have many either, my smallest is a 10, largest 25. I do recall running into a security torx problem in the past, and now I find there
are 'variations'. - paralobe, plus.

There are also a couple of little square Robertsons in my bit set of torx.

--
Mike Easter

A few weeks ago a young neighbour of mine asked i he could borrow a torx sreedriver if I had one (some). At the time I had never heard of them.

Alan
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: alt.os.linux.mint

pinnerite wrote:

A few weeks ago a young neighbour of mine asked i he could borrow a torx sreedriver if I had one (some). At the time I had never heard of them.

Your GMT tz looks like .eu or .en; but around here we have huge
warehouse stores called Home Depot which has a wealth of so many things,
incl tools. The section which has screwdrivers and related tools is
VERY extensive and a lot of fun to shop. I was there not too long ago
because I wanted to improve my collection of 'little bitty' screwdrivers between what I had for eyeglass repair and an ancient sewing machine screwdriver passed down from my mother.

It is a lot of fun to shop in that section; I discover all kinds of
things I never 'imagined'.
--
Mike Easter
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: alt.os.linux.mint

On Tue, 7/22/2025 2:27 PM, pinnerite wrote:

On Mon, 21 Jul 2025 12:50:57 -0700
Mike Easter <MikeE@ster.invalid> wrote:

pinnerite wrote:

Down to B&Q and bought the two smallest sizes. 19 & 12.
Got home to find the 10 was OK but I also needed an 8.

(Learning some torx) wow; I never knew they went from 1-100. I know your
19 above is a typo for 10.

By design, Torx head screws resist cam out better than Phillips head or slot head screws.

I don't have many either, my smallest is a 10, largest 25. I do recall
running into a security torx problem in the past, and now I find there
are 'variations'. - paralobe, plus.

There are also a couple of little square Robertsons in my bit set of torx. >>
--
Mike Easter

A few weeks ago a young neighbour of mine asked i he could borrow a torx sreedriver if I had one (some). At the time I had never heard of them.

Alan

You never stop collecting things like that, because the
next appliance you buy, the screws on it, you don't
have any in the toolbox. Some of the ones I've got, I
don't even know the correct names for them.

As for the Slo-Blow fuse inside the ATX PSU,
that hardly ever blows. That's "F1" in the upper left
corner of the schematic.

http://www.pavouk.org/hw/en_atxps.html

If you had a Kill-A-Watt meter, and the fuse had opened,
the current flow from the L connection would be zero, and
that's an easy way to determine it is open circuit. If
some level of current is flowing into the supply, then you
know the fuse F1 is good.

Reasons for current to flow:

1) Leakage from L to shield, via the filter caps on the front end.
Maybe 2mA max.

2) Some amount of power (1 W, 7VA) to run the +5VSB circuit
(but not running any fans).

3) When some fans are spinning, the switcher is operating,
you will see a bit more power than (2) will be observed
on the power meter.

Paul

--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: alt.os.linux.mint

On Tue, 22 Jul 2025 11:36:46 -0700
Mike Easter <MikeE@ster.invalid> wrote:

pinnerite wrote:

A few weeks ago a young neighbour of mine asked i he could borrow a torx sreedriver if I had one (some). At the time I had never heard of them.

Your GMT tz looks like .eu or .en; but around here we have huge
warehouse stores called Home Depot which has a wealth of so many things, incl tools. The section which has screwdrivers and related tools is
VERY extensive and a lot of fun to shop. I was there not too long ago because I wanted to improve my collection of 'little bitty' screwdrivers between what I had for eyeglass repair and an ancient sewing machine screwdriver passed down from my mother.

It is a lot of fun to shop in that section; I discover all kinds of
things I never 'imagined'.

--
Mike Easter

None of the stores within a five mile radius stock an "8".
One is coming from China, due 10 August!

Meanwhile a replacement Corsair 850watt has been delivered and tested.

On the assumption that the failures were due to short circuits, I
adhered fibre washers to a new Gigabyte B650 Aorus Elite AX motherboard
(where do they dream up these names), mounted it with one of the Ryzen
7 CPUs installed and powered up.

The fans started up but a warning LED (the CPU one) illuminated.
I tried a second Ryzen 7, same result.

How can I find an engineer with the equipment to test both CPUs in NW
London, UK?

--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: alt.os.linux.mint

On Fri, 25 Jul 2025 12:51:41 +0100
pinnerite <pinnerite@gmail.com> wrote:

On Tue, 22 Jul 2025 11:36:46 -0700
Mike Easter <MikeE@ster.invalid> wrote:

pinnerite wrote:

A few weeks ago a young neighbour of mine asked i he could borrow a torx sreedriver if I had one (some). At the time I had never heard of them.

Your GMT tz looks like .eu or .en; but around here we have huge
warehouse stores called Home Depot which has a wealth of so many things, incl tools. The section which has screwdrivers and related tools is
VERY extensive and a lot of fun to shop. I was there not too long ago because I wanted to improve my collection of 'little bitty' screwdrivers between what I had for eyeglass repair and an ancient sewing machine screwdriver passed down from my mother.

It is a lot of fun to shop in that section; I discover all kinds of
things I never 'imagined'.

--
Mike Easter

None of the stores within a five mile radius stock an "8".
One is coming from China, due 10 August!

Meanwhile a replacement Corsair 850watt has been delivered and tested.

On the assumption that the failures were due to short circuits, I
adhered fibre washers to a new Gigabyte B650 Aorus Elite AX motherboard (where do they dream up these names), mounted it with one of the Ryzen
7 CPUs installed and powered up.

The fans started up but a warning LED (the CPU one) illuminated.
I tried a second Ryzen 7, same result.

How can I find an engineer with the equipment to test both CPUs in NW
London, UK?

I forgot to add the DDR RAM was also installed.
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: alt.os.linux.mint

On Fri, 7/25/2025 7:55 AM, pinnerite wrote:

On Fri, 25 Jul 2025 12:51:41 +0100
pinnerite <pinnerite@gmail.com> wrote:

On Tue, 22 Jul 2025 11:36:46 -0700
Mike Easter <MikeE@ster.invalid> wrote:

pinnerite wrote:

A few weeks ago a young neighbour of mine asked i he could borrow a torx sreedriver if I had one (some). At the time I had never heard of them.

Your GMT tz looks like .eu or .en; but around here we have huge
warehouse stores called Home Depot which has a wealth of so many things, >>> incl tools. The section which has screwdrivers and related tools is
VERY extensive and a lot of fun to shop. I was there not too long ago
because I wanted to improve my collection of 'little bitty' screwdrivers >>> between what I had for eyeglass repair and an ancient sewing machine
screwdriver passed down from my mother.

It is a lot of fun to shop in that section; I discover all kinds of
things I never 'imagined'.

--
Mike Easter

None of the stores within a five mile radius stock an "8".
One is coming from China, due 10 August!

Meanwhile a replacement Corsair 850watt has been delivered and tested.

On the assumption that the failures were due to short circuits, I
adhered fibre washers to a new Gigabyte B650 Aorus Elite AX motherboard
(where do they dream up these names), mounted it with one of the Ryzen
7 CPUs installed and powered up.

The fans started up but a warning LED (the CPU one) illuminated.
I tried a second Ryzen 7, same result.

How can I find an engineer with the equipment to test both CPUs in NW
London, UK?

I forgot to add the DDR RAM was also installed.

Is the ATX12V power for the CPU plugged in ?

There can be two connectors, one is preferred.

The implementation of status indicators, uses the "dumbest method possible".

For example, imagine you put a flip-flop on the board, driven from
a GPIO, and a single particular CPU instruction clears the flop.
The flop can drive the CPU fail light. If the jump instruction
to the well-known location fails to execute (the CPU crashes on the
first instruction, an instruction that does not depend on the
presence of DRAM), then the flip-flop is not cleared and so the CPU
failure LED stays illuminated. This means, the CPU is not necessarily
"writing to the LED", it's a passive scheme where a failure to issue
a "clear" to the LED, leaves the CPU fail LED lit.

If the computer stays jammed in RESET, this causes the CPU fail to
come on, until you can get the thing out of RESET and the CPU is
sent off to the well-known location for its first instruction fetch.

The standoffs use a ground-ring, meaning they are intended to
touch the ground of the chassis-standoffs. There is usually a keep out
zone in the layout, around the standoff, such that moving the motherboard off-center, does not crush any SMT R or C components.

On branded motherboards with "DO NOT POPULATE" standoff locations
on the bottom of the board, adhesive paper labels, arrow-shaped,
point at the standoff locations that "MUST NOT BE POPULATED". Always
visually examine the secondary side (bottom) of the motherboard, for
any labels of this type. This is not a normal practice, of booby-trapping boards, but as a system builder, you are expected to be a Ninja and
familiar with all the tricks.

Paul

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From Newsgroup: alt.os.linux.mint

On Fri, 7/25/2025 7:55 AM, pinnerite wrote:

On Fri, 25 Jul 2025 12:51:41 +0100
pinnerite <pinnerite@gmail.com> wrote:

On Tue, 22 Jul 2025 11:36:46 -0700
Mike Easter <MikeE@ster.invalid> wrote:

pinnerite wrote:

A few weeks ago a young neighbour of mine asked i he could borrow a torx sreedriver
if I had one (some). At the time I had never heard of them.

Your GMT tz looks like .eu or .en; but around here we have huge
warehouse stores called Home Depot which has a wealth of so many things, >>> incl tools. The section which has screwdrivers and related tools is
VERY extensive and a lot of fun to shop. I was there not too long ago
because I wanted to improve my collection of 'little bitty' screwdrivers >>> between what I had for eyeglass repair and an ancient sewing machine
screwdriver passed down from my mother.

It is a lot of fun to shop in that section; I discover all kinds of
things I never 'imagined'.

--
Mike Easter

None of the stores within a five mile radius stock an "8".
One is coming from China, due 10 August!

Meanwhile a replacement Corsair 850watt has been delivered and tested.

On the assumption that the failures were due to short circuits, I
adhered fibre washers to a new Gigabyte B650 Aorus Elite AX motherboard
(where do they dream up these names), mounted it with one of the Ryzen
7 CPUs installed and powered up.

The fans started up but a warning LED (the CPU one) illuminated.
I tried a second Ryzen 7, same result.

How can I find an engineer with the equipment to test both CPUs in NW
London, UK?

I forgot to add the DDR RAM was also installed.

Ask a computer store "if they do builds".

Any computer store which sells computer-case, PSU, mobo, CPU, DRAM,
will have a technologist who assembles these for customers. For an
extra 100, they install an OS and drivers.

At Best Buy, this is the Geek Squad, and you can bring
a PC in for test at the desk there. Always back up the hard
drive, when presenting valuable materials to these sorts of people.
There have been many many cases of the C: drive "getting erased".

My computer store has room for two guys to build PCs, and the staff count
in the build area varies with time of year and state of economy.

When the technologist tests, they test the same way I do, "swapping" and
"fault isolate to nearest three components". They don't have bed-of-nails structural test capability or JTAG scan chains or a 2.5D Xray machine for checking BGA balls. They might have a multimeter :-)

To be a good tester, you have to know the bringup sequence of the equipment. What parts matter. Sure, all sorts of unlikely faults can develop on a board, and a bulk tester like the technologist can only do so much.

So lets see if we can kinda guess at AM5 bringup.

1) Board starts in RESET. A power bug watches the rails, noticed the rails
out of spec at startup, and asserts RESET. The pulse width of the raw
(starting) RESET signal might be half a second. (Anything more than 100mSec
is usually enough for PLLs to lock in on synths.)

2) User must take finger off RESET button. Defective RESET button keeps
the board reset determination in RESET. The computer can be operated, without
the RESET twisted pair, and the RESEt switch, connected to the FP header.

3) The PSU must assert its Power_Good signal. The onboard switching
converters must assert their private Power_Good. These are all gated
together, to make a "Global_Power_Good". When Global power is good,
that is a reason to leave RESET.

4) Once RESET is deasserted, the clock gen is running. There is 33MHz for the
BIOS flash chip on the LPC bus.

5) We don't start executing right away. First, the PCH (Southbridge) copies
the AGESA code from the BIOS chip and shoots it via a serial link, to the
CPU. The signature of the AGESA code must be good, for the CPU to accept it.
Now, the CPU is ready.

6) Since RESET is deasserted, the CPU sends out its first instruction fetch
at a well-known address. This address happens to be the boot block of the
32MB BIOS flash chip. The boot block contains code which allows
"checksumming" the main BIOS code block. The main BIOS code block is
not executed, unless the checksum passes. On some special Tyan/Intel
or Tyan/AMD server boards, the CPU won't start unless the main BIOS
code signature also passes (says it's Tyan or whatever).

7) The boot block is executing. There is no graphics output capability in
the boot block.

8) Code can execute without DRAM being present. For example, once a few instructions
of boot block code have run, the boot block code can clear the CPU LED.
(the CPU LED having been set via RESET).

9) Boot block hands off to the larger code block. DRAM commissioning begins.
Special CAS cycle is sent to the DRAM, telling it of its contractual
obligation to the CPU memory controller. Both devices must know and agree
with this parameter, to talk to one another (CAS is in the SPD table).
...

So what do we have so far ?

1) ATX12V connected ? MAKE SURE its in the correct hole.
There is a defacto correct connector, but the manual may not draw attention to this.
2) Is BIOS content sane ?
3) Is AGESA version modern enough for Ryzen 7 ?
4) Is board Power_Good there ?
5) Is RESET deasserting (and AGESA transferring, and first instruction fetching) ?
6) Soon after this, we should be programming the DRAM and fiddling DRAM LED.

Assumes CPU is properly seated, fans are running.
+5VSB did not overload early and cause fans to stop spinning.

Since your power is staying up, your fans are running now,
we're no longer asking you to "check for fan twitch indicating overload".

Paul
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