Mobo or PSU?

new2spcr · Post by **new2spcr** » Sat Dec 12, 2009 3:09 pm

Hi all,

I'm having intermittent and spontaneous problems with one of my computers at work that I really don't know how to diagnose.

The system** is around 1 year old and has been working flawlessly until recently, just couple of weeks ago - when I pressed the start button and the monitor only showed flickering lines... so when I opened the case I noticed the graphic card's fan had stopped. Applying a gentle nudge on the blades it started up spinning again but spontaneously stopped againn after couple of minutes. So I turned the computer off, checked that all cables were okay and booted up again. No problem. Fan was spinning nicely.

Next morning I went to work and booted up the PC.
Monitor /graphic card were okay, no flickering whatsoever. But during a long POST, I got this message:

"S.M.A.R.T command failed" or similar, but the booting continues (with garbled screen) and I manage to shut down the computer properly by experimenting with Tab and Enter.

I swapped out the sata cable and replaced it with a new one, thinking it might be a glitch in there somehwere and booted up; no problem. Ran a Seatools session and nothing bad was found. All sectors okay, all SMART tests passed.

Couple of days ago, upon booting the system, I get the same monitor garble thrown at me and I immediately open up the case to see if the darn fan has stopped again. Nope, it's spinning!
No POST problems either.

I shut down the computer and reboot - no problem.

What can it be? I suspect it might be the PSU going bad, or could it be the mobo?
If it's the mobo, wouldn't the problems occur more frequently and more or less same problems showing every time?
The mobo has solid capacitors afaik, and a visual inspection didn't reveal anything weird.

I could send this box in and ask the shop to honor the warranty, but problem is I can't afford having the box taken away from the office more than couple of hours tops. The shop by the way, insists they need to have it at least one week and won't send any replacement or a unit (PSU for example) until they find out what's wrong with it.

** System spec:

# 1 APLUS Case Qubic, Svart Midi tower
# 1 Chieftec PSU ATX 400W
# 1 Intel Core 2 Duo E4700 2,60 GHz
# 1 Asus P5Q PRO, P45
# 1 Corsair TWIN2X 6400 DDR2, 2048MB
# 1 XFX GeForce 8400GS
# 1 Seagate Barracuda 7200.10 250GB SATA2
# 1 Samsung 20" Wide Syncmaster 2032BW

Note that system runs cool, it's not overclocked. Only mods I've done to this system is a graphic card fan swap (Zalman) and a HDD suspension.

Thanks for any advice.

Post by **NeilBlanchard** » Sat Dec 12, 2009 7:32 pm

Hi,

I would check the capacitors on the motherboard power regulation section (usually between the CPU socket and the I/O connectors on the backplate) and see if any of them are bulging and/or are leaking "goop". If they are, then you have found the problem!

new2spcr · Post by **new2spcr** » Sun Dec 13, 2009 1:47 am

NeilBlanchard wrote:Hi,

I would check the capacitors on the motherboard power regulation section (usually between the CPU socket and the I/O connectors on the backplate) and see if any of them are bulging and/or are leaking "goop". If they are, then you have found the problem!

Hi, thanks. I will check those out tomorrow.

RoGuE · Post by **RoGuE** » Sun Dec 13, 2009 7:58 am

I would lean towards a PSU problem honestly. Just for the simple fact that your graphics card acted weird, then your HDD failed SMART.

Seems to me they arn't getting the right voltages sometimes?

I could be wrong. Do you have another PSU you can swap in to test the platform? If so, it may be worth the several hours of work to do that and find out which component is causing you trouble.

new2spcr · Post by **new2spcr** » Mon Dec 14, 2009 1:54 am

RoGuE wrote:I would lean towards a PSU problem honestly. Just for the simple fact that your graphics card acted weird, then your HDD failed SMART.

Seems to me they arn't getting the right voltages sometimes?

I could be wrong. Do you have another PSU you can swap in to test the platform? If so, it may be worth the several hours of work to do that and find out which component is causing you trouble.

@ Neil - all my capacitors are solid ones, no leaking or bulging.

@ Hi Rouge, that's what I'm suspecting too - the PSU perhaps delivers minor spikes in the voltages, but only occasionally and only during startup.
I actually ripped out an old PSU from another computer today (a generic PSU 350 W that came with the chassi, an In-Win) and will have to see if problems persists. You're right it might take many hours to narrow it down since the problems aren't really consistent.
One thing I noticed though when I went into the BIOS after the new PSU was installed, was that the BIOS screen froze at some point and the keyboard wasn't usable. Other than that I have no problems with corrupted BIOS or such.

kittle · Post by **kittle** » Mon Dec 14, 2009 1:08 pm

Something else to consider.

Since the system is 1yr old, its possible you have some dust buildup. I would snag a can of compressed air, and clean out the gpu fan and the cpu fan (make sure you pull the power plug first).

Its also quite possible that your failing (or failed) PSU has taken out other components in your system, or pieces of other components, and its just a matter of time until the rest of the system goes south on you.

new2spcr · Post by **new2spcr** » Tue Dec 15, 2009 1:46 am

kittle wrote:Something else to consider.

Since the system is 1yr old, its possible you have some dust buildup. I would snag a can of compressed air, and clean out the gpu fan and the cpu fan (make sure you pull the power plug first).

Its also quite possible that your failing (or failed) PSU has taken out other components in your system, or pieces of other components, and its just a matter of time until the rest of the system goes south on you.

Hi,

No dust build up here...
Ah, don't scare me. A PSU going bad seldom drags other components with it, so I've heard. *crossing fingers*