Molex connectors!! 6x Hard Drives and 2x GPU's
 

Question regarding my HDX card -
My 5,1 Mac Pro from 2010 has 6 SATA slots (2x for the optical drives, 4x on the motherboard). I currently have 6 SATA hard drives occupying those 6x SATA slots.
I also have dual ATI Radeon 5770 cards, each requiring power from the molex connector on the motherboard.

Therefore, I am stuck with no remaining power for the HDX card. Since I'm unable to borrow from the SATA ports, what's the appropriate cable I need to send power from my Mac Pro motherboard both to the PT HDX card and the ATI Radeon GPU at the same time?
Or should I not do this and get an external power supply to power the HDX card instead?

Re: Molex connectors!! 6x Hard Drives and 2x GPU's
 

From memory, those 5770s have two 6-pin PCIe power connectors each? Both of which need to be connected otherwise they won't work properly. I'm not sure that leaves you many options. An additional power supply is probably the go. Another option would be to replace the two 5770s with a single, newer, more power graphics card. There are plenty of details around about running something like an RX580 or RX7970 in these machines with a HDX card. The 7970 in particular is readily available, flashed for OSX use. They also have the benefit of being about 350% to 400% more powerful than a single 5770.

Just a thought.