Trying to find the problem

[CHiWuaN]

I just received this PC from a friend since he's having some problems and I'm trying to fix it. So far, I haven't been able to find the problem, but I can share the following information. Maybe someone has had the same experience and can point me in the right way.

- PC randomly reboots or freezes.
- Some reboots occur before Windows loads, so that tells me it's a HW problem.
- Sometimes, before the machine freezes, the screen starts to change colors randomly (it looks like when you apply a different color theme under Windows, I mean, you see the shapes, but colors start changing)
- The machine has support for DDR and SDRAM. Currently a 256 PC133 Dimm is being used.
- Motherboard is all in one, including lan, video, audio. It's a ECS motherboard, but can't remember the model number right now.
- If machine doesn't reboot on the first 10 min, then it doesn't ever.
- I tried stressing the system to find the weak spot. I can run Prime95 and Sandra tests forever flawlessly.
- I tried switching the power supply, but still, random reboots before Windows loaded (and some after it loaded too)
- HD is clean, no viruses.
- Only card is a CNR Modem
- CPU is a P4 1.6 with retail fan, working.
- Sometimes after rebooting, the screen won't show up again. I turn it off, then back on, then the system speaker starts beeping (2 long beeps, then silence, then repeat). After letting it off for a couple more seconds, the system starts again.
- I removed the heatsink, and everything seemed to be fine (contacts clean, etc), then plugged back in and same problem.

Any suggestions? I once thought it was the memory, since sometimes before locking it started changing colors (and the video uses the main RAM for display), but I don't have a spare DIMM (neither SDRAM or DDR) to try it, and in case the problem is the RAM, how could I be running multiple stress tests on memory without failing?

Thanks in advance.

 

[n0cmonkey]

Test the ram with memtest86.

 

[CHiWuaN]

First pass with Memtest is done, and still no errors.

 

[imported_raybay]

Replace the memory with that from another machine, one module at a time. Sounds like memory to me, and Memtest86 isn't always reliable with modules such as SDRAM PC133 and beyond. Let it run, if it will, with the substituted memory, even it only a 64 MB module. If you can't obtain alternate memory, run Memtest86 for 24 hours with never ending passes. Run an alternate video card. Disable rather than remove current driver, then install and run at least two other Video cards. Finally, exchange modems with another machine. I am always astonished by how often that innocent little do nothing modem is the cause of problems like the ones you describe. Disable the on-board audio, as it, too, can be an insidious little trouble maker. You have already tested the normal stuff. I would not expect it to be the power supply or CPU, unless the CPU shows head damage. But you might have a flakey motherboard. This you can test, by trying all components in another system.

 

[Sianath]

If you are bugchecking with windows running, the stop codes will be listed in the system event log. If you see a large variety of them in there (all different codes) then it's almost guaranteed to be a hardware problem.

If it's always the same code with identical (or close) parameters, post what it is so we can see what's up.