1x with riser not working

[faille]

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?

[Nivco]

I had the same problem few days ago. Setup was : 4 cards (5870s) on mobo, all with extender (16x and 1x). Ubuntu won't boot with a card on extender (Xorg failing) but will finally without. I had no issue in BIOS however.
The solution in my case was to directly connect the card with the (faulty?) extender on the mobo, leave the others with extender. (Actually, 2 cards up, 2 cards down on mobo, more space means also more vent)

I'm very curious about what caused that weird crash, if anyone got a clue...

[Reckman]

You need to short the pciex1 card detection pins.

[faille]

You need to short the pciex1 card detection pins.

You mean like I already said I tried doing without success?
Admittedly I should have used the term Short instead of Bridge to avoid confusion with crossfire, but yes, I've tried it without success.

I also admit I may not have shorted correctly, but seems to be quite simple and hard to not get right.