Hardware Computer locking up.

[FAST6191]

Recently my computer decided to start locking up seemingly at random. Very rarely it will reset itself (and then lock up just before/after POST). It seems to be proportional to time since being turned on/locking up last in some cases but not in others.

No new hardware added. No new bios updates. All devices within stock/suggested settings: no overclocking, no overvoltage, no tighter timings, I even reset the bios settings).

No new software (not to mention it locks up sometimes before it even launches the drive and even as early on as graphics card splashscreen/test although I can get a blinking "cursor" when that happens, I tried without one and I booted from a livecd)

I cleaned the dust (there was a bit but nothing major).

I pulled it apart, cleaned it all and put it back together. No effect.

I redid the thermal paste (and it dropped about 20 degrees from the running temp but it was fine before it).
It then ran for just under 2 hours and locked up again. Temperature was well within limits for the entire time.

I tried without drive and booting from CD.
I removed as much as I could (1 stick of ram, only one graphics card, no hdds, no DVD drive, no wireless, all USB, sound and firewire removed bar the built in ones, only a keyboard attached: still locked when I watching the BIOS clock tick over). I do not think it is my PSU on the fritz, if necessary I will pull it apart and test it properly but it does not seem likely.

I discharged the capacitors I could see (shorted terminals), it ran OK for a while but as it seems random I am not willing to draw any conclusions.

In conclusion
My thoughts were heat: nothing appears to be warm to senses or IR of the crappy camcorder I have. Cleaned and redone thermal paste, airflow is as good, if not better than it has ever been after the rebuild. Not to mention timing is very odd: thermodynamically stuff should not be able to overheat and cool and overheat again at the rates I am seeing.
Connections all appear fine and I did do a strip down and rebuild.
My next thoughts were dead capacitor: I have not tested them all yet but they seem to be working, most just seem to be signal smoothing based as well and lockups are too random for it to be that.

Unfortunately I lack the equipment to test each part (the other problem with high end machines), the only people I know with capable stuff are out of the country and PC shops are either PC world (£50 for walking through the door and I would be willing to bet my problem is "spyware" and the only solution a £100 set of AV software) or independents who I trust even less than most politicians ("your machine is broken but I have a state of the art 386 you can have for a £1000"), are incompetent (they gained their skills at PC World you know) or are those who are out of the country

Edit: my specs:
http://gbatemp.net/index.php?showtopic=428...t=0&start=0
I have a different CD drive a a crappy wireless card I salvaged (it has been working for about a year now though). My machine has been well (ab)used since I built it so I would not be too shocked if parts are dying but I would rather not have to get new stuff, especially if I am overlooking something obvious.

 

[rhyguy]

Nvm

Try another psu/mb if you have one

 

[xcalibur]

Well if you think that your issue is being caused by adware/malware, try this online scan.

http://www.pandasecurity.com/homeusers/solutions/activescan/

 

[Alerek]

Can you see if he still has that 386? XD

I've had similar problems in the past, one time was an overheating issue, other time I had a bad piece of ram in there..maybe try booting with only one piece at a time?

 

[suppachipmunk]

I have been having this same problem too. But my computer is about 7 years old. So I am thinking of replacing the PSU of that computer to see if I can even power it on anymore. It is outdated but I can use it for certain things. Hopefully someone can give a solution as this may solve my problem as well.

I am looking into a PSU for myself, but since it is proprietary sony, I may wait to see if that is indeed the culprit.
But the PSU is the only thing that I can think of.

 

[Psyfira]

If you find out let me know

Random freezing is a bastard to diagnose because you can't reproduce it; in 2 years I've never managed to suss out what pulls my laptop down. I've done a lot of reading up about freezing PC's and it sounds like you've ruled out all the usual suspects (dodgy memory, HDD, overheating). And PC World are just a rip off; forking over £120 just for a diagnosis probably done by someone who knows less about hardware than you (that was the fee they quoted for a laptop 3 years ago so I bet it's gone up since then. And that phone call ended rather quickly I can tell you.)

 

[CockroachMan]

Could be a lot of different stuff..

'

Your PSU could be malfunctioning and not sending the right amount of energy..

or, modern mother boards can detect the CPU temperature and turn off if it's too high.. it could be broken and not getting the temperature right..

or it could be just a virus/malware..

If possible, try testing it with another PSU/mobo/CPU.. and see if the problem is still there..

 

[notnarb]

Your computer seems recent enough to warrant having an older computer lying around, try the psu from that? If it froze on the bios screen, it couldn't have been the cpu or the ram. The randomness of the freezing also points to the infamous variable of electricity, leaving just the motherboard and the psu

 

[FAST6191]

For those still reading the problem was tracked to a dodgy PSU (unable to put out anything resembling the correct voltage let alone stable to the point I was able to detect it on my £12 digital meter) and the worst ever application of thermal paste on the northbridge and southbridge (from the factory as well). As an example there were small gaps in the paste (I do not know how many of you have applied thermal paste or done any plastering but the thing you get where you have some grit in there happened) and what was there was beyond coupling and into actual insulation range and the paste seemed to be the cheapest silicon paste you could imagine.


Now deciding whether a new motherboard is worth it (the *bridges sat at around 80 celcius I figure for about a year and about 80% of that time it was powered and even overclocked so electromigration has probably long set in and gone most of the way to killing it). The bridges are cooled by two copper heatsinks (each having a pipe to another set of smaller chips and a polymer thermal pad to couple the secondary part) held on with "fish hook" (think spear head that opens out) plastic screws with tiny metal springs the other side.
From here it is either another thermal pad and hope the gap is small enough, a tweak on the xclamp fix (split washers) or full blown custom attachments (ok most likely just an alan bolt bolt head and a nut).

This whole ordeal and the last couple of months with other stuff has seriously put me off anything by asus in the future.