Hello everyone, I know that this topic is been around for a while, but reading forums for hours now, I still didn't find a fix for my problem. So hopefully someone here can help me with this. My Mac Pro is from 2009, flashed to 5.1. Running two GPUs, an ATI Radeon HD 5770 and a ASUS Turbo GeForce GTX 1070 TI. In OSX The Radeon works fine but the GeForce has weird display errors (See the images attached). The strange thing is, that the GeForce runs normally on the Windows partition. I suspect the power supply to be the Problem. The GeForce has an 1x 8-Pin power connection, that I connected with the standard 1x 6-Pin cable. Adding an adapter to have an 1x 6-Pin to 1x 8-Pin connection didn't solve the problem. Today I figured out that each of the PCIs only deliver 75W, the PCIe another 75W. One solution would be to use both PCIs for the GeForce with a dual 6-Pin to 1x 8-Pin cable. But then the total power would be still only 225W. The specs of the GeForce say that it needs at least 500W. As mentioned, thats only my suspicion. The problem might have another source. If anybody knows a solution and could help me with this, I would be really grateful. Already spent so much time trying fix this GPU issue. Thanks!