what is the difference between these cards
The p8z77 v pro has more power phases so it will be better in overclocking.
It has an extra usb 3.0 header and can be useful in the future.
It comes with an extra bracket to add 2 more usb 2.0 ports and an e-sata
I would pick the pro, I have it and its amazing, i have no problems. Its also more future proof due to the extra usb 3 header