Hi dear MacRumorians, having a 5,1 Mac Pro with 12x 3,46 GHz and currently using an unflashed GTX 980 in it, I was wondering if my machine can handle 2 GTX 1080's... - without an extra PSU. I ask, because "Bear Feats" did a benchmark with the new Pascal driver on Sierra 10.12.4 and on their benchmark list, they use 2 1080's in a single Mac Pro. They said there: "In case you haven't noticed, we added the results for a pair of GeForce GTX 1080s. We could not resist seeing how much speed they added to the 'multi-gpu aware' apps. All we needed were 6pin-to-8pin adapter cables to use the Mac Pro's factory PCIe 6pin power cables. There is no startup screen with un-modified Pascal series GPUs. One of our GTX 1080s had a modified ROM courtesy of MacVidCards and, therefore, provided a normal startup screen." So, sorry if this has been already discussed here (haven't found a thread for this), but can anybody tell me, if it is possible and if: where do I have to pay special attention for ? - what kind of cards should I buy (with less power consumption)... - do I need a flashed one not only for the booting screen, but also for a better communication for macOS... Helpful answers are very appreciated Edit: I saw on a another test (http://barefeats.com/mvc_pascal.html), that he uses the power supply from the optical bay: cMP>1080Ti*2 - DUAL NVIDIA GTX GeForce 1080 Ti GPUs in x16 Slots 1 and 2 of the 2010 Mac Pro (with power supplemented by lower optical bay) cMP>1080*2 - DUAL NVIDIA GTX GeForce 1080 GPUs in x16 Slots 1 and 2 of the 2010 Mac Pro (with power supplemented by lower optical bay) Is there a workaround to follow ?