Step 1: Take down that wall!
Seriously. I did this, expecting i'd have to jump a pin on my GPU to make it detect. But nope. It works just fine! The GPU autodetects the bandwidth of the slot and runs at 1x speeds.
Works just fine.
No need for these risers anymore!
By the way, if anyone wants to know. The method I used to take it out is by putting a cut-out piece of a PCI connector in the slot to protect the pins, and then using a hot soldering iron to melt off the wall. Took about 5 minutes.
Now, I have two 7870's running on a $30 Pentium 4 board.
Light mining rig base. 380 kh/s stable with mining scrypt.