Hello! This is my first post here, was looking to get some help with a Mac Pro I acquired. Let me give you an idea of what I did to this point. Completely took it apart, dusted it all out, reapplied thermal paste, and removed the non functioning superdrives. I also installed a 240GB SSD, and a 250 GB HDD. Lastly I installed an EVGA GTX 1060 6GB edition as my gpu. I was able to get the patched version of High Sierra installed with no issues and then installed the nVidia web drivers. Everything seemed alright. But I noticed that sometimes the machine will crash to a black screen, then all the fans kick on to high. Sometimes it'll do it right after it Chimes, sometimes 30 seconds after it hits the desktop. Then I thought it was an issue with the patched OS, so I went back to El Capitan with the original 8800GT and I haven't had the issue occur yet. Will check when I get off work though because it seems to happen the longer it sits off. I was going to try a patched version of Sierra next to see if maybe it was a high sierra issue because I really want to use the GTX 1060 I bought for it as I will be using it to edit video. The Tech specs are as follows: Early 2008 Mac Pro 3,1 2 Xenon 3.0Ghz Quad Cores 12GB DDR2 Ram GTX 1060 6GB 240 GB Sandisk SSD + 250GB WD Blue Hopefully someone out there can help me, I'd really appreciate it as I have run out of ideas aside from trying Sierra. Thanks! Update - Each time this happens, it does chime and pass post, not once has it ever failed posting.