Bad CPU or bad MB

[Pirates vs Ninjas]

Is there any way to tell whether a problem is occuring in the motherboard or the CPU, without swapping known good components? My Dad's PC starting crashing last week, and I have been working on the last few days. There were no major changes in terms of hardware/software. As of now, I cannot get to the logon screen in Vista, startup repair and boot CDs will not run correctly, often dying with a BSOD (BAD_POOL_HEADER is a common error). Memtest86 lights up like a Christmas tree in the first few minutes. At first I thought it was a bad RAM stick, but i have tried several known good sticks all with the same result. I don't want to waste money on something that might not be the problem (already did this with a new RAM stick). Is there anything further I can do to isolate the problem to either the CPU or the MB?

 

[MagnusTheBrewer]

Have you tried resetting the BIOS?

 

[mpilchfamily]

First things first. Check to make sure the CPU cooler is securely fastened in place. We need to rule out the system overheating.

 

[Pirates vs Ninjas]

I do not think it is a BIOS or overheating issue. No BIOS settings were changed when this behavior starting occuring and the CPU temp is reading a steady under 30 degrees.

 

[MadAmos]

If you have a DVOM it wouldn't hurt to check the PSU voltages, but if you are confident that the memory you have tried is ok in other systems mobo seems likely.

 

[mpilchfamily]

What CPU is it and what are you using to report CPU temps?

 

[Pirates vs Ninjas]

Its a Sempron, checking the CPU temp in BIOS.

 

[Pirates vs Ninjas]

Well it wasn't the MB. I have a spare PSU I am going to try