Just had to box my 2013 Mac Pro up to return it for diagnostic tests for the second time since New Year - first time was two weeks ago - one morning the computer wouldn't turn on. Tried all the usual things, fuses, pmc, power cord - no joy. Boxed it up and returned it to my supplier who I bought it from in May last year - it reached them a few days later powered up normally and passed all diagnostic tests, so they sent it back to me. I work a lot in 3D modelling and rendering in Maxon Cinema 4D - this machine is my daily workhorse Once it arrived I powered it up and it all worked fine, I got back to doing a bit of modelling in Cinema 4D and slowly started it doing renders again until Wedneday morning this week when it wouldn't turn on again!! Now I'd had some time to think about this and realised when I'd returned it to the supplier for service I'd boxed it up with some silica gel. So I popped the computer into it's original box with several large sachets of silica gel, and after 6 hours drying time the computer was back up and running - it seems that condensation must be forming inside the mac pro!! I powered the computer up again Thursday morning and decided to set it rendering a couple of shots for my current project - it rendered through the day fine, all the way through the night until just after 10:00am this morning when it spontaneously shut down and refused to power on again! Very disturbing when you walk into the room and this happens The computer is now boxed and awaiting a courier return to the supplier again for further testing. The operating temperature specs for the computer specify a minimum temperature of 10C - I checked the room temperature this morning, 15C so well within operational boundaries. The 2013 Mac Pro has always seemed to run a bit warm when performing intensive rendering, but it seems a bit ridiculous that I can't use it in this way during the winter months!! It hasn't even been particularly cold this year! I've used Mac Pro's, G5's G4's for years in exactly the same way as this machine and never encountered such an issue - I really hope it's just me. Has anyone else come across a similar problem or have just been unlucky with this machine?