Re: Computer turns on and then just dies

On Tue, 11/26/2024 12:44 PM, s|b wrote:
> On Mon, 25 Nov 2024 17:33:05 -0500, Paul wrote:
> 
> 
>>> I'm making a note of that. I bought the PC in 2012, so there's a good
>>> chance it's the CPU and not the PSU that causes the shutdown?
> 
>> Unlikely.
> 
> )-:
>  
>> If a heatsink falls off the CPU, the temperature shoots up to 200C,
>> the thermal protection does not engage immediately, that
>> could damage a CPU.
>>
>> But really, with the heatsink fastened to the top, there is
>> thermal inertia (mass) and the temperature does not shoot up
>> quite as rapidly.
> 
> That's disappointing, sort of. But I do get to play with the paste.
>  
>> It's more likely a capacitor is leaking near the CPU socket,
>> if the board won't start.
> 
> Well then it's removing the hard drives and dump the tower at a recycle
> point! If I'll bring it to a computer repair store they will charge me
> an arm and a leg.
>  
>> But your case, your initial symptoms were an overloaded +5VSB.
>> I suggested measuring the current, as one way to ascertain
>> if there is a specific problem with the combination of
>> components. If something is shorted on the motherboard,
>> then the problem (box shuts off), may still be present
>> with your spare supply installed. You would put in the
>> spare supply. The LED would be lit for a minute or two,
>> then go off on its own. That could be an overload of +5VSB
>> for example.
> 
> I'm learning new things here. It's my brother who knows electricity; I'm
> 100% sure he's got the equipment to measure.
> 
> I checked the PSU that I hopefully can use:
> 
> AOpen
> Model no: Z400-08FC (400W peak)
>  
>> Modern motherboards (yours is modern enough), have THERMTRIP.
>> If the CPU goes over 100C to 120C or so, THERMTRIP causes
>> PSON# to be deasserted and the PC fans stop spinning, and
>> 3.3V/5V/12V are then powered off. You can have a shutdown
>> due to a thermal issue. The Asus LED remains lit when that happens
>> (a THERMTRIP).
>>
>> But the thing is, you told us that the Asus LED, which
>> monitors +5VSB, that went OFF. That's an indication of
>> a power supply problem, not a THERMTRIP. THERMTRIP will
>> not turn that LED off.
> 
> OK, tnx. Does this also fit in the fact that I sometimes get to the BIOS
> (however briefly it is) ?
>  
>> The LED then, is key to determining whether you have
>> a "NEW" or "DIFFERENT" problem than the first one reported.
>>
>> 1) Swap out power supply. Put in known-good supply.
>> 2) Record symptoms again. Does PC shut off as before ?
>>    Does the Asus LED stay lit after the erroneous shutdown ?
>>
>> Report back.
> 
> Will do when you confirm I can use the other PSU. It's ATX, so I'm
> guessing yes?
> 

AOpen  Z400-08FC (400W peak)   [Numbers are different than the 380D supply]

    5V  3.3V  12V1  12V2  -12V  +5VSB    [ no  PCIe  1 x 6-pin ? ]

   20A  20A   10A    13A   0.3A   2.5A
   \       /  \        /
     130W      23A common
   combined     source

12V2 is CPU
12V1 is peripherals, PCIe slots

"ASUS F1A75" it is probably the 3870K entry below.

A guess would be, it can't be over about 100W or 12V @ 10A to allow some
efficiency room. The Z400 has 13A available for the 10A load, which is
pretty full.

https://www.asus.com/me-en/supportonly/f1a75-v%20pro/helpdesk_cpu/         <=== check the table, your CPU
                                                                                is in that table
   AMD A8-3870K (AD3870WNZ43GX, rev.B0, 3.0GHz, QC, L2:4M, HD6550D, 100W)

The 12V1 has 10A for things like a video card (if present). If
you took the video output of your APU (CPU has GPU inside), then
the biggest drain after that would be HDD and ODD, and 10A is
enough for that (12V @ 1.5A ODD, 12V @ 2A HDD).

The AOpen is enough for a basic PC.

CPU: AMD-A8-3870 BLACK EDITION WITH RADEON HD 6550D
Tower/PSU: ANTEC-NSK4482B-EC 380 WATT
Graphic card: AMD-AP38G160U2K  <=============================== I can find no info for this.
SSD: INTEL-SSDSC2CW120A310 120GB 520 SERIES 34NM SATA III2 .
HDD: WESTERN DIGITAL-WD5000AAKX 500GB 16MB SATA600 7200RPM
CD/DVD (re)writer: LITE-ON-IHAS122-18 SATA 22X DVD-RW

I'm not getting a match on your video card.
Both search engines aren't matching on "AP38G160U2K"

The graphics function inside the 100W APU is HD6550D.

The thing is, your Peripheral supply 12V1 is only 10 amps,
and that's not going to be enough for much of a standalone
video card in an expansion slot.

The motherboard has four video connectors on the plate.
It has DVI-D, VGA, HDMI, DisplayPort. These run off the APU (CPU+GPU) chip
and so to make the PC work, you don't even need a separate video card.

   https://www.legitreviews.com/images/reviews/1721/asus-f1a75-v-pro-layout-6.jpg

Normally, if you had purchased a separate video card, it would
go in the long, dark-blue slot on the left of this picture.

   https://www.legitreviews.com/images/reviews/1721/asus-f1a75-v-pro-layout-5.jpg

  ( https://www.legitreviews.com/asus-f1a75-v-pro-motherboard-review_1721/3 )

The thing is, the AOpen supply is unlikely to have a PCI Express 2x3 power
connector on it. And a small video card might need a power source like that.
That's why knowing some details about what you are actually
using for video is important.

Next to the long, dark-blue4 slot on the left of the picture,
is the round CMOS battery CR2032.

Using your multimeter, you can connect the black lead to the chassis metal
(the VGA screw would do) and the red lead to the top of the CMOS cell, and
that should read +3.0 volts on the 20V scale of the meter, if the cell was new.
If the PC has been sitting in a closet for more than 3 years, then
the CMOS battery will be flat, and you will need to purchase a
replacement CR2032 to put in the round socket. I have replaced a lot
of these here, because the PCs sitting in the junk room, wear that
battery down quickly. Only a few PCs will not start, unless that
battery has at least 2.0V on it. The battery is a bit higher than
3.0V when new.

The motherboard will not "remember" the BIOS settings you enter, unless
the battery is functioning. The clock for example, will show the wrong time.

Using your debug technique of "swap it out", you do not need to
replace the CR2032 right away. However, if you fit the Z400 supply,
and the Asus LED lights up, but pressing the power button does not
work, then replacing the CR2032 would be the next step.

*******

summary: Please examine the contents of the PC and confirm how your
         video works. Is there an add-in card in one of the long slots ?
         Or are you using a video connector in the group-of-four connectors
         in the Legitreviews picture ? It you are using a separate video card,
         there may not be enough power for it, or a connector to feed the
         card power.

   Paul