Recommend getting a PE4C V3.0. http://forum.techinferno.com/enclosures-adapters/7941-bplus-pe4c-3-x-2-x-discussion-10.html#post135033 You have a PCIe 2.0 capable system so recommend getting the eGPU adapter with best PCIe 2.0 (Gen2) signal integrity which is the PE4C V3.0. Your HD7790 has a TDP of 85W. So could even get a 120W AC adapter to power it. Then again, I'd suggest getting a NVidia card such as a GTX750Ti/GTX960/GTX970 over AMD due to it's superior driver features (x1 pcie compression