Opinion on computer problem please.

[nelsonm]

hi all,

i have a desktop that:

1. after a time, the display goes blank and the keyboard and mouse do not respond but the pc remains powered on with the case and cpu fans running.

2. it will also restart on its own.

I have disconnected all components except the dvd drive and and booted the system using the ubuntu live cd but the same thing happens.

The PSU tested ok.

hardware diagnostics tested ok except for some undefined value in smbios.

Any ideas?

 

[Kitten Kong]

When you say the psu tested ok, how exactly did you test it? If it is still doing it bare bones, I would suggest you actually swap the psu, for a known good one, and take it from there.

Also have you checked the temps in the bios?, the restarts could be attributable to too much heat.

 

[nelsonm]

i used the FrozenCPU brand PSU tester.

However, i agree, i will swap out the PSU to rule out all components except the mb and cpu.

 

[TechguyUK]

I had a similar one to this the other day. After a quick check inside I found that the graphics card was overheating due to a sticky fan (user is a heavy smoker).

I cleaned out the fan and it ran fine after.

 

[joydivision]

I've seen plenty of PSUs which have tested ok but I have known for a fact are faulty. It sounds like the 12v rail is struggling to provide enough ampage from the symptoms you describe.

Could be overheating too though and a million other things but do swap out the PSU first.

 

[Joseph@Dagon]

I actually had a similar problem on my own PC at home.

Ended up being the vga card overheating. Swapped it out for a new one and its been great ever since.

The thing is though, i even ran some burnin tests, and everything showed up fine. So you shouldn't always rely on those test.

 

[numnutz]

had one a few months ago. like you tested power supply tested fine. swapped everything, memory, cpu even nuked it.it was power supply, pulled out a 380watt put in a 430watt have not heard back from him

 

[wtigger]

This scenario is mostly power supply in my experience also. The PSU testers only tell you that you have the voltages, but NOT if they can handle the load.. I've tested so many PSU's that a tester said was OK then replaced the PSU and the problem was fixed... FWIW...

 

[NorCal Internet]

I actually had one that was the reverse... Unit powered on w/o any video. If you left it powered on for 5 minutes, turned it off and back on again, it would have video.

Client said it took a little longer during the winter for it to "Warm up". He would actually turn it on in the morning, go take his shower, and come back, power cycle it, and then check his e-mail.

He was fine with this, it was when it started rebooting constantly that he brought it to me...

Turned out the video card was bad, causing the video issue... During one of the video dead periods, he'd rebooted the machine while it was apparently doing an update, or booting, or something, and corrupted the OS.

A simple chkdisk fixed the rebooting.

 

[nelsonm]

One thing i have learned in all years i've been repairing pc's is that problem can be anything and not always obvious!

I had one pc that appeared to have a graphics card problem. The screen would tear, flicker and blank out. It turned out to be the hard drive.

Bad components can drag down other part of the system by sending altered or grounded electrical signals.

In this case, i replaced the PSU. But the problem is still there. Soooo it has to be the mb or cpu since there are no other components connected to the system other than the dvd drive and that was replaced too.

The next step is to stick a graphics card into the mb to rule out the integrated graphics chip. If the problem persists, then i will replace the mb with a cheap compatible mb to rule out the mb.

 

[nhicktrush]

I'm interested to find solution for this problem, hope to find one.. please share it here guys so we will know exactly what to do in case it happens on our pc. Thanks.

 

[AJ.]

My vote goes to a problem with a faulty video card.

 

[nelsonm]

ok...

I tried a pcie and a pci graphics card - the problem persists. The mouse, keyboard and monitor stopped functioning after about 5 mins to currently 30 secs after boot. The mb is an Intel DH55TC. Since the Intel H55 chipset interface on the DH55TC mb handles both the USB and display ports, i would conclude that it is the source of the symptoms and, if no other chips are faulty, most likely the cause of the problem.

thank you all for your input.

 

[nelsonm]

Update...

While it looked like the mb was the problem, it now looks like it was a ram issue all along.

Hardware diagnostics initially ruled out the ram but after trying other ideas and having the system's problem continue, i tried another hardware diagnostics test. This time the system would hang before the diagnostics could finish the memory test.

So i started physically testing each stick one by one in the system. The system worked perfectly with all but one stick. Just to be sure, i ran the system with the good sticks once for each slot - no problems. The system failed consistently with the suspected bad stick in each slot.

So for those who suspected the ram - you where right!

 

[aburwig]

Dang iT!!! I was too late to the game here! I was about to mention my experience with my son's computer about a year back. It was a hand me down XP machine, so I had a few problems to solve from the get go. But, eventually, it began restarting on its own, blanking out, very similar to what you had. Like others have said, all my tests came out normal, but the problem persisted, So I simply stripped it down and began swapping out components one at a time. In the end it was a single stick of memory that was causing the issue.

I have also seen a similar issue with video and network cards as well, and it is true that testing software will not always be enough to solve the problem. Sometimes you've just go to do the exploratory surgery and remove the offening bits.

 

[nelsonm]

it is true that testing software will not always be enough to solve the problem. Sometimes you've just go to do the exploratory surgery and remove the offending bits.

you go it dude!

I think I'll start a new thread shortly and enumerate what i think is the most efficient and least time consuming steps to take when diagnosing a problem and invite others to make their opinions on their most efficient steps.

 

[frase]

Why dont you check the event viewer for a descripted cause?

This does sound like a video display driver issue, maybe even a 'TDR' error [Time Display Recover]. I have had these in the past, check your RAM timings in BIOS and correct the DIMMS slots are used as well.

 

[nelsonm]

I did check the event viewer - nothing to lead me to a ram issue.