You should have no problem on medium hitting over 60FPS. On high, not so sure. On max details and 2xMSAA your GPU gets around 45FPS at 1080p: www.guru3d.com/index.php?ct=articles&action=file&id=23557&admin=0a8fcaad6b03da6a6895d1ada2e171002a287bc1
^^Take note that tech site used a 4.4GHz overclocked Core i7-5960X CPU. Not sure how that would impact the FPS compared to your Xeon 3.2GHz CPU in performance.
i can run crysis 3 ultra-high mixed setting on 65-75 FPS.
Crysis 3 =/= GTA V.
But just saw your resolution comment. At that resolution, you might be able to do the same with GTAV in high settings. 1080p is much more taxing on the video card, and 1440 and 4K more so.