I've already setup one computer onto a 1x slot with a 1x to 1x riser cable and it works fine, running a 6950 off it. It did not need any bridging to be done on the motherboard 1x slot.

Trying to do to the same on another computers with 5850's, but it's not working. If i try to bridge as I've seen in a few guides, then the computer won't boot up. If I leave the bridge off, but the card connected, the system boots up, but doesn't detect the 2nd GPU, I've tried with both dummy plug and monitor plugged in.

Am I missing something or does anyone have any suggestions?