i got 2 PCI-PCI-e converters from ebay, i had issues with win7 enabling the device within my mining rig (asrock X58 extreme with 4 6950 and 1 5670 getting 1.6 GH/s),
however on boot the converter worked fine on a second mobo with the 4870 plugged into it, i still need to do more investigation, but i don't want to disturb my miners!