Nvidia: missing sm bus and coprocessor

I have an Asus M3N78 pro motherboard, my pc is custom built. I had a GeForce 9600 GT card in my computer. I have been using standby mode a lot. I went to turn on pc one morning by tapping spacebar on keyboard and my screen was green. I tried changing cables, etc and nothing. I then removed the video card and put in a GeForce 8500GT card. It worked for about 5 mins and then I got a BSOD message about nv4_disp. I tried restarting and that didnt help. I then got in with last known good configuration and downloaded latest drivers for the card from nvidia. Same BSOD problem. I then went into control panel, add remove progs and removed all nvidia drivers. NOTE there were several nvidia progs that could be removed. After doing this and restarting I got back to desktop and then had default vga controller, and had missing coprocessor and sm bus controller. I went into safe mode with networking, and tried installing card there. Same BSOD problem. I am at my wits end with this one. Ive even gotten the hardward ids and vendor ids and they all come back to nvidia. HELP, ILL GLADLY REPLY WITH ANY INFO YOU MAY NEED TO HELP ME.

 

Op Sys is XP sp3.

 

Hi my friend , you could try this

http://majorgeeks.com/Driver_Sweeper_d6171.html

uninstall all leftovers of the driver , afterwards you have done a clear installation , this is the official site

http://www.asus.com/Motherboards/AMD_AM2Plus/M3N78_PRO/#download

download the chipset driver :wave

 

I currently show in add/remove progs as having nvidia drivers, nvidia graphics driver 306.23, nvidia hd audio driver 1.3.18.0, nvidia nview 136.28, and nvidia physx system software 9.12.0604 although the system isnt recognizing the device at this point. so which nvidia removal should i do from here before i use the driver sweeper. and then install fresh new drivers and then the chipset?

 

ignore the above as those programs weren't available to be removed when attempting to do so.

I tried your suggestions and it didnt work.

 

Do you have any yellow mark in Device Manager menu ? :wave