Question Computer will start without auxillary graphics power plugged in, but not with it plugged in


Sep 13, 2013
Hello all,

I built a PC about two years ago with the following specs.

Intel i5 8600k
Some 120mm Corsair AIO Liquid Cooler
16 GB Geil Evo Potenza Ram
ASRock 370 Sli/ac Motherboard
Samsung 970Evo 250 GB M.2 Drive
Some generic 3 TB HDD
Thermaltake Toughpower Grand RGB 650 W PSU

This pc worked great for about two years, when suddenly programs which strained the graphics card would begin to crash with increasing frequency, until I could no longer play/use them (R6 Siege, and Firestrike/Time Spy). Prime 95 did not have any problems, leading me to believe this was either a GPU problem, or a PSU problem, wherein the PSU was not supplying stable power to the GPU under high loads. The computer still worked for all other programs and always turned on without fail.

Today, I attempted to swap out my current PSU for a brand new Corsair TX650M PSU. I swapped out all the wires, and the PC would not start. I have determined that the PC will start up with the auxillary 8-pin power to the GPU unplugged, where it will display the message "please shut down and plug in the PCIe cable(s) for this graphics card." After plugging in that cord to the graphics card, when I press the power button nothing happens at all. I can repeat these results.

I am at a complete loss and have no idea why this is happening. The computer "worked" until I swapped out PSUs, and now it will only start up* without the 8-pin power plugged into the GPU.

*When I say start up I mean the LED's light up, all the fans start spinning, and then the screen changes to the above "plug in the power to the GPU" message.

Thank you,