PC locking up during games

I built my pc in Jan. to play Everquest2 and other high graphics games, but when I get on the game, it freezes, and there is a high pitch noise in my speakers.

Mobo P4S800D-X
3.2 P4
2G RAM
Chaintech Geforce 6600 GT 128m
soundblaster audigy 2
Rosewill 550W PSU
lite-on dvd player
dvd-r
80G western Digital SATA HD
3 case fans

I have tried a number of things to fix it, I have ran memtest86, removed sound card to see if that was the problem, unplugged numerous things to see if it was a power issue (I had bought the 550W to upgrade a 450W psu thinking that was the issue, I was sadly wrong), heat isnt an issue, my cpu runs at 41C on average, Mobo runs at 30C on avg. I have updated my bios, my SiS chipset agp drivers, my vid card drivers, soundcard drivers, swapped the ram sticks with each other, and one thing I did happen to notice was that my old vid card (geforce4 ti4200) worked on the games that I play where my 6600gt didnt.
I have tried running 3Dmark, but after it loads up nothing else comes to the screen, just a black screen. Are there any older drivers that would work better than the new ones? Any ideas, cuz I am fresh out and feel like punting my pc onto the front lawn...

 

If it is OK with the old geforce but not the new one maybe the card is cactus. Still under warranty hopefully.

You've done just about everything else to troubleshoot.

 

Yup you got a whacky Video Card. I never did like the quality of Chaintech.