I'm trying to disable the onboard video on a gateway gt5220. The current bios setting is to only use the onboard video if a card is not detected but it doesn't seem to be recognizing the EVGA 512-P2-N738-LR GeForce 8400. The video card appears to be getting power as the fan does turn on. I've tried resetting the CMOS but that hasn't helped. I've also tried re-seating the video card. The motherboard is a NVIDIA GeForce 6150 AM2 uBTX 1394. Any suggestions?