Hello,
I had switched from Mac Pro to PC similar to your list but only one 980TI but I have RED ROCKET X card installed. Also, I’m running Windows 8.1.
6K R3D up to 30p works no problem with Redcine-X but 60p won’t playback without dropping frame.
4K projects in Resolve 12 beta 3 with 6K, 5K materials work fine. But some OFX plugin like Neat Video get stuck. This might be happening even if the project is in HD but setting the RAW to full-debayer.
I’m little stuck sometimes what to do with Prores when customer asks (although Redcine-x Pro does export prores, but from the Resolve, I can’t do prores), getting by, by using XAVC output.