Power Supply Help

[StAndrew]

Rig is updated in my sig. I just bought a SeaSonic Platinum 1200W PSU and it runs just fine until I try to overclock the GPU's.

When I try to bump up the GPU clocks, the drivers crash or I get a blue screen and one time the computer shut off. I think I may have miscalculated the power supply requirement and want to verify before buying a new PSU by connecting my old PSU to share the load.

My plan was to use the working OP1000W Silverstone I have to run two of the video cards (don't have the right connections to run three) but I can't get the PS to turn on with the jumper. When I jump the green and black wire the PSU ticks and the fan either ticks on and off or sometimes spins up a little but you can tell its getting intermittent power.

I've tested it on my old system and it boots up just fine so the PS does work. Do I need a load on the 3 and 5V rails to run the 12V?

[StAndrew]

For some reason I cannot get this PSU to power any of the GPU's. I bought a power monitor and running Unigine Heaven, I'm only pulling ~900W at the wall. I still can't get these cards to overclock much more than 1150 core without artifacting and/or crashing. The 12V rail is rated at 100amps so I don't think the PSU is the issue...