Bad CPU vs Bad Motherboard

[light65536]

I have an i7 860 CPU and Gigabyte p55-usb3 motherboard. I've not had any problems but the other day the computer crashed and I had a hard time to get it too reboot beyond bios. I now have it booting into Windows but if I put any load on the CPU, i.e it is allowed to step up from 15x multiplier to 21x or 22x multiplier it crashes.

I have replaced or changed out the following parts with no change:

* Power supply
* Graphics card
* Unhooked everything else
* Loaded fail safe defaults in the BIOS
* Stress testing memory is OK but testing of CPU esp FPU results in insta-freeze

I am pretty sure it is either the CPU has went bad or the motherboard is bad. But, I'm not sure which. It sure sounds like the CPU but I"ve never had an INTEL cpu go bad. How can I determine if I need a new CPU or a new motherboard?

The computer will boot fine provided it is at 15x multiplier. If I run Prime95 at 15x multiplier its okay but if I try to run Prime95 at stock it insta-crashes. Temperatures are good.

Also, #2 I believe this is a retail chip under warranty, how long does it take for Intel to send out a new chip?

 

[jemm]

Intel has an excellent RMA service -- it is fast and they don´t give you any hard time. It takes about 1 week depend on your location.

 

[dish_moose]

I went through same thing on an office machine - after I replaced the mobo it turned out to be cpu - my last suspect.
-Bruce

 

[light65536]

I tried to flash my bios and it looks like it failed but strangely enough.. now everything is working. Very odd but good nonetheless.