I use these risers from eBay, very cheap and they do the job.
They fit in 16x and 1x slots.

I had one of those, the soldering was so shit that it shorted out and killed a 5770 and a 5830 of mine!
Hack the redundant end off the the long end, take the blue tape off and check every connector with a magnifying glass. Thats what I do now.
Also, no need to short any wires and put power in afaik, mine work fine
I tested all the risers on my old PentiumD with nVidia 6200 card before using them in a rig