I just helped my friend install a huge brand new heatsink in his Dell Dimension 4600 and at first, we got RAM install errors. But after fixing those slowly, we stumbled upon another problem. The video card, an AGP Geforce 5500, was being tempermental. We would see the boot screens, the XP boot screen, and get to the desktop. But after about five minutes, the screen would go blank and lose signal and never regain it. We thought it was a loose connection of the cord to the screen, but it wasn't. We thought it was a bad insert and took out the video card and blew out some dust, but still no improvement. So, we put in a Geforce 5200 that we had lieing around and now its doing better. Anyone know what the problem could be and how to fix it? Thanks.