Hello everyone, I hope you're all doing great. A friend of mine asked me for some help to try and revive an older model Mac Pro (is there any way I can verify which iteration of the hardware it is without turning it on? Let me know if this would be possible, and necessary to help you all help me! Thank you!) and first I thought we just needed to do a fresh OS install and be good to go -- the Mac Pro has been sitting for the past, hmm, six years or so, without ANY maintenance, any upgrades, nothing, not even file management/folder organization had been done right... The problem was that the computer would not pass the initial grey screen (no Apple), but by booting it into Safe Mode, we were able to retrieve and backup important documents, and then I got the "Go" to just wipe the two drives and try a reinstall. Through Target Mode, I erased the drives, and then tried to boot the computer with various OS DVDs, but I would always get the grey prohibited sign on boot. As a last resort, I just connected the Mac Pro to my MBP via Target Mode again, and installed Mavericks on one of the drives (I would have tried to install an older OS, but the installers don't open on Mavericks... right?). Now the Apple logo appears on boot on the Mac Pro, but then it goes to the grey screen and it gets stuck. Hm. What should I do? Can you guys help me out? I would be so, so thankful! Sorry for the somewhat long post!