I've done a bit of reading on here about graphics card upgrades and the like. I've got a 2010 MacPro 5,1 with its stock ATI 5870 1gb card, and it is running OS X El Capitan, and using the 27" LED Cinema Display and a 20" A1081 as a second screen (with mini display port to DVI adaptor). It is getting a bit old now and I'd like to upgrade it, but the talk of flashing the graphics cards and non-EFI compatibility makes me shudder a bit. I'm an old hand at building PCs, but the Mac is something I prefer not to tinker with too much. What's the best bet for an easy upgrade as far as the graphics card goes? Would a GTX780 Nvidia work (6gb would be nice), or am I going to have to look at a eVGA 680 "mac edition"?