Question PSU malfunction causing CPU to overheat, cannot event display POST screen

Jul 25, 2022
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Hi,

Specs details:
PSU Cooler Master Silent Pro Gold 550W. Motherboard Gigabyte 970A-D3, CPU AMD FX-8320, Cooler Master Evo Hyper 212, Graphics card Asus GT 1030 passive cooling, case Fractal Design Define. The whole computer was assembled in 2014.

I take great care of my computer (no dust, thermal paste new). But unfortunately I made a blunder by placing the desktop case on a carpet floor. I forgot the case has an air intake from the bottom . The obstruction has caused the PSU to work harder. With the summer heat it was too much and the PSU had gone under.

Symptoms began by the screen freezing. Hard reset, power off/on cycle, etc. could not restart the OS. The screen remain blank, not event the BIOS screen could be displayed. Opening the case, the most obvious sign I have seen is actually the CPU cooler which is uncomfortably warm. All fans works OK. No smell of burning. All other parts of the computer are cool. The CPU just get hot within a minute as soon as the power is on. I just feel that by touching the aluminum fins of the cooler. Unfortunately I forgot to touch the PSU casing otherwise I would know it is the culprit. The screen displays nothing. No beep pattern b/c the case has no speaker.

In daily operations, this CPU never got warm during its lifetime, I have never seen the CPU cooler getting even slightly warm. The usage is office work and casual surfing. No gaming. The hottest part used to be the heatsink on the chipset. The whole computer works great since 8 years.

I have unplugged the peripherals one by one and rebooted each time. The last part I tried to swap was the PSU. And then the motherboard can reboot and the computer works like before.

QUESTION: what is the technical reason for a PSU to malfunction in such a way that it only overheats the CPU while not being able to boot at all? I would like to give some hints to the person to whom I am giving away the PSU. Or maybe should I throw that PSU in electronics recycle?
 
if ure outside of operating system, then CPU doesnt have running any power saving features...thus it will heat alot, not even speaking about bios which mostly locks cpu usage at 100%

so have you replaced your PSU?
and yes you should just recycle it, its out of warrranty
 
Jul 25, 2022
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I have already replaced the PSU. I am going to post on local classified ads to give away the one which is in troubles. Someone may know how to fix it

if ure outside of operating system, then CPU doesnt have running any power saving features...thus it will heat alot, not even speaking about bios which mostly locks cpu usage at 100%
I don't understand. On any computer, once you power off, and power in again. You are automatically outside of the OS. In my case, as from a power off status, once I power on, the CPU heats quickly and I feel the warm within a minute. The BIOS doesn't even start (the screen remains blank). So I suppose this is something happening outside of BIOS, outside of OS.
 
I have already replaced the PSU. I am going to post on local classified ads to give away the one which is in troubles. Someone may know how to fix it



I don't understand. On any computer, once you power off, and power in again. You are automatically outside of the OS. In my case, as from a power off status, once I power on, the CPU heats quickly and I feel the warm within a minute. The BIOS doesn't even start (the screen remains blank). So I suppose this is something happening outside of BIOS, outside of OS.
when you press power button, bios already runs in like one second, without it you wouldnt even have working PC, all hardware detection is done by bios...even before anything shows up on screen
 
Jul 25, 2022
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when you press power button, bios already runs in like one second, without it you wouldnt even have working PC, all hardware detection is done by bios...even before anything shows up on screen
Oh really? Thanks for the info. What do you think had happened causing the BIOS to do something on the CPU to make it overheat so much?
 
Jul 25, 2022
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what temperature you get on CPU when you run cinebench?
Cannot run now b/c I have assembled another computer last weekend. Cannot bother that machine too much b/c this is a work machine. The motherboard + FX-8320 + RAM has been retired. Would need to wait sometimes to assemble that mobo set on a spare machine. Also I never run cinebench. Hope it's not too complicate.

Looks like I am in tricky situation. I thought the symptoms were a known PSU issue pattern. But if this require a long investigation, then maybe we can forget it. I have no intention of reparing that PSU. Just asking out of curiosity.
 

Karadjgne

Titan
Ambassador
Psu has nothing whatsoever to do with cpu temps.

You cooked the psu because it gets its airflow from underneath and you smothered that with carpet.

As soon as you push the power button, Bios is activated. It's Bios (Basic Input/Output System) that actually turns on the pc, goes and finds all the equipment, checks the power status (POST, Power On Self Test) of the equipment and loads any necessary system drivers to operate the pc. It's roughly a 50% load on the entire pc, including the cpu.

Once Bios is satisfied that everything is functional, that's when Windows starts and takes over control of the pc functions from Bios. After that boot time, the load on the pc drops from @ 50% to idle or @ 5%.

If your cpu at idle runs @ 33°C in Windows, it's going to run @ 45-50°C in Bios.

Figure that's @ 113°F to 122°F, very much like the same temp as the hood of a car in the middle of summer. In a word, Hot! By the time the cpu cooler starts seeing cpu temps of 70°C, it's hot enough to burn your fingertips.

Stop touching the cpu cooler thinking that your fingers are a good judge of what the cpu should be. They aren't, not even close.
 

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