I have the HP 6200 Pro Microtower computer which has a 320 90% psu. I am looking to upgrade the current GPU, a Nvidia 650, to a 960 or AMD r9 380. The Motherboard takes a very strange connection pin that isn't standard on any PSU, which is where I ask my question. I have seen a user for the HP 8200 Elite state that he had the system minus the GPU run on the stock psu and then had the PSU in the bay power the GPU. Can I do this? Any help is appreciated, but help with people with experience with HP desktops is even more welcomed. Thanks!