WOT doesn't like AMD GPU overclocks :/ but doesn't surprise me for CPU overclocks either. Is an archaic DX9 engine
However how you managed 120fps? I have tried on GTX1080 @2190 core at 2560x1440 with the 6700K @ 4.8, 4930K @4.5, 4820K @ 5Ghz and never managed to see more than 108 on zoom out mode. Only zoom in and that 117-118 never 120. And exactly the same perf regardless if GTX1080 was stock, or OCed at 2190. Same applied to the Nano also. Same FPS regardless if is 1000/500, 1000/550 or 1100/550.
I don't understand how you have never seen more than 118fps in WOT, using a 4790K at 4.6 & a 980SC I have seen 127fps, I have a screenshot somewhere I will dig it out and post it.