Hi, I have a new radeon 9550 256mb agp GPU. I'm upgrading my pc from a old Nvidia geforce to this new one. So i took out the old card and put in the new one, hooked the monitor in and turned the pc on. Here's the problem nothing comes up on the screen, no BIOS and the mointor light doesnt turn green it stays at yellow. Also the power light on the front of the pc turns off after a few seconds (the computer is still turned on). Any help would be great. Thanks.