Game freezing

q6600
4870 1gb
gigabyte ep45 ds3r
2gb ocz ddr2 800
1kw antec

It all started when I got my new gpu. It would bsod when playing games and browsing the web. The bsods usually say the display driver has stopped responding and something about ati2dvag. And usually happend when the computer wasfirst turned on. If it was on for awhile it was ok. As time went on, it usually wont bsod when browsing the web and games just freeze and I have to restart. I tried rmaing my 4870, and while I was I used a old x1050 and it worked fine playing cod4 on all super low. The new 4870 didnt help. So then I tried putting it in the second slot and that didnt help. Then someone told me to change the pcie thing in the bios from auto to 100. I tried that and put it back in the first slot and when playing cod4 it still freezes sometimes. So I tried my friends 4650 and it still froze randomly when playing cod4. Ive tried reinstalling, different psus, and only using 1 stick of ram. Nothing worked. Mem tests and hdd test say everything is ok. Its weird how the x1050 works but the 4870 and 4650 dont. So basically, now I can do things like browse the web just fine, but when I play cod4 it freezes randomly sometimes and a milisecond of audio loops really fast and I have to restart. There are no bsods cause I left it frozen for awhile and nothing happened. Any ideas?

Ive tried tons of different versions of drivers and nothing helped. I think I have 9.6 now. What igp? And I tried a different psu and it didnt help.

Maybe you got a flacky ps, or maybe a stick IS bad and memtest missed it, bad stick in last slot caused me headaches too.

I was thinkink about it being the mobo, but I wanted to eliminate that possibility. I doubt the psu is flaky cause Ive tried different ones (585w powering everything 450w powering gpu) I have an idea. Im genna go to best buy, then buy some parts, and see if anything helps, and then return it. And the message is something about ati2dvag and something about the display driver stopped responding.