Just got a 5870 off ebay to crossfire with my 5970, need a little help

So did you not get it with your PSU?

Your PSU should have already have four PCI-E cables coming out of the box.

you only need a 6-8 converter and they cost about 8bux... you dont need the corsair specific 1 as there a standard fitting...

It only comes with two cables with each cable having two (6+2)-pin PCI-E connectors on them for a total of four PCI-E connectors.

The OP should contact Corsair and explain the situation and they just might be pleasantly surprised.

If you only have 1 PCI cable your psu is messed up and you may need to contact the manufacturer if its saposed to have 2. Also you can get a molex converter and if your worried about running the molex because they're kind of ugly you can get extensions to run from the gpu to the converter so it can be out of the way