What we do:
-1 or 2 BMD decklink quad cards, 4-8 hd-sdi in
- Deck link minimonitor card, 1 hd-sdi out
- 2 monitors, multiview and vmix UI
- no streamig (we use an other computer for that) or specific encoder card
- recording 4 inputs and master mix
- video delay for 4 inputs (60s buffer/preroll) and clip recording about 10s

What we have though:
- 32 GB DDR3 1600Hz memory (or should it be 64GB?) video delay buffering?
- intel i7 four cores (or should it be the fastest six core i7-4960X 3.6 GHz)
- one 256Gb SSD for software, 2x 564Gb raid for recording (is it possibe to point another third drive for video delay recordings?)
- Asus GTX780TI-3GD5 NVIDIA GeForce GTX780 Ti 3072 MB ( Or should it be titanium which has 6000 MB memory?)

In which point the CPU starts to get load? I have understood that most of the work is done by GPU.