I am signing off.
If there is nothing on device manager and we accept that the ram is OK, then although there is no error recorded on device manager, there may still be a driver that windows will not accept.
Start with the graphics driver on the link I sent you and you said that you had 12.3 - try installing 12.4
It is on that link as the latest one.
Reboot after install and see if it still BSOD
If it does try this and see if it BSOD on a clean boot
Having clean booted it CHECK that your anti-virus is still runnning if NOT do not use the web and go back to msconfig and recheck the anti virus entry on startuphttp://support.microsoft.com/kb/929135
PLEASE read the clean boot procedure carefully especially the caution regarding restore points
HAVE you used any registry cleaning program, booster make it go faster etc. They are generally unwanted, uneeded and known for causing problems
If all that fails, then when I return I will post a link so that I may see what you have installed etc.