Motherboard not recognizing new video card

I have a system with an ASUS P5D Deluxe board that will not recognize a new video card.

The old card was/is a Sapphire 4850, powered by a 6-pin power connection. Although it works (displays BIOS post and boots into Win 7 OK), it has overheating issues and needs to be replaced.

I'm attempting to replace it with a newer ATI card. I've tried two so far (both powered directly from the board; no external power required). In both cases, the PC turns on along with the video card cooling fan; however nothing shows on the screen. I've tried both a VGA and DVI connection; no luck. The P5D Deluxe board has three PCi-E video card slots; both the old and new card are inserted in the slot closest to the CPU.

Since the old video card works in the slot (and the cooling fan on the new one turns on), I've pretty much ruled out a motherboard issue.

The new card is a PowerColor PCI Express 2.1 x 16 Radeon HD 6570, 1GB DDR3.

Any tips or tricks to get this thing working are greatly appreciated. Thanks in advance.

 

Disregard previous post.

Somehow, after leaving the PC on for about 20 minutes, the ASUS Express Gate screen suddenly appeared. :confused :confused :confused