BSOD help MACHINE_CHECK_EXCEPTION

I get the blue screen of death when ever i try to play games such as counter strike source or day of defeat source. Ive been able to play all my games with no troubles for a long time and i just started geting the blue screen two days ago. I havent made any new changes in hardware and no new drivers and havent downloaded or installed anything new. The blue screen says MACHINE_CHECK_EXCEPTION. Which i have come to find out means that im having a hardware error and it is most likely my RAM, mobo, power supply, or processor that needs to be replaced. And ive come to find out the error code is
BCCode : 9c BCP1 : 00000000 BCP2 : BAB3C050 BCP3 : B2000040
BCP4 : 00000800 OSVer : 5_1_2600 SP : 2_0 Product : 768_1

So how do i know which one is the problem?

My specs:

xfx nvidia 650i mobo
xfx nvidia 8500gt video card
2gigs of ddr2 600 ram
intel core 2 duo E6600 procesor
230w power supply
Windows xp home

run memtest 86+ from a cd or floppy for at least 7 passes.

your psu is also grossly underpowered.
replace it. google psu calculator and add 30% to the results for cushion.

I fixed it! if anyone else is having this problem i would recommend reseting ur bios settings to the default.