Wehn i use Bonic with seti @ home i get blue screen says one of my cores is messing up, its not a heat problem becuase i got a artic Cooling unit it works fine on Windows vista Ult. Any solution to the problem i had to stop colulations to this to avoid system data loss

OK you haven't gotten any error WU's for your CPU

the HSF is irrelevant unless you can tell if its actually cooling anything. There's always a possibility that your paste is old, unevenly spread, or has bubbles that prevent cooling. Its best to get a hardware monitor to check into this. CPUz has 3 things you need. HWmonitor, GPUZ, and CPUz. The HW monitor will let you see all your temps and voltages in 1 stop. I've never actually had a CPU lose a core but I assume it can happen. If anything I'd bet on the mobo before I'd right off the CPU

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In a rich man's house there is no place to spit but his face.
Diogenes Of Sinope

As Skildude suggestion, despite your assumed elimination of the CPU as a suspect, I would still start with proper diagnosis by running Prime95, which is a program very similar to SETI@Home in that it stresses your CPU extensively. If you experience Blue Screens with Prime95 as well, then you have a repeatable problem.

I would then start by checking the temperature of your CPU to see how hot it's running. If it appears to be running cool, I would move on to testing your RAM. Failing or overheating RAM can cause system instability just as an overheating CPU would. Memtest86+ is a great tool for extensively testing your RAM for errors.

If your CPU and RAM do not turn up to be faulty, then I would suspect a power issue, possibly with an underpowered power supply unit (PSU). Running at a high system load can cause weak PSUs to trigger Blue Screens. Unfortunately, the only answer to this is to either replace it or reduce SETI@Home's CPU usage (and by extension it's power consumption).