What are your GPUs? If your lack of PSU cables is the problem, then you could use PCIE splitters like this:
Been using this for almost a year now without any problems at all.
Sorry guys. I should have been clear. This is what I need. Is it true it gets plugged into the CPU slot?
So, Im not sure this is even it. My PSU has 4 cable cable slots for 4 GPU's. Im only using 650w out of the 1200w my PSU is rated for. I want to add a 5th GPU, but have no where to plug it into the PSU.
By using these cables your cable slots for GPU will doubled, you can add 4 more GPU's and a total of 8 if your PSU could handle it.
next problem would be powering up your risers