Getting blue screen after hardware change

[skaler]

I have an ASUS A8Ne motherboard that I put a new CPU in and a new video card. When I bought the computer, all was well. The OS is WinXP pro. The original CPU was an Athlon64 3200+ and the Video card was a Geforce 6800 pcie. I bought an Opteron 170 and a GeForce 7900GS. I kept the original drivers which were already installed to drive the 6800. I didn't change the drivers but just simply installed the video card. It performed just fine running HALO and Half Life2. I swapped out the CPU next, and the BIOS recognized it correctly. I then installed the dual core optimizer from AMD. I also updated the BIOS. I get a blue screen when I wake the computer from standby. I have a sleep key on my keyboard(a Dell)-ps2 connector. I can wake the computer with the stroke of any key. It is then that I get the blue screen. If I cold boot the computer, all is perfect. The games run as expected, and I notice no problems. I did reset the RTC on the MB by pulling the battery, repositioning the jumper for 10 to15 seconds, and then resetting the BIOS to default. Even though the MB is capable of overclocking, everything relevant to that is set to AUTO. I have also uninstalled and reinstalled the video driver, but I used the existing folder where the previously installed driver was located. The blue screen is pretty consisitentin terms of what it reads. Any suggestions on how to get rid of the blue? Thanks.