Problem: every game doesn't run..

HI,

i have tried some games, but every game doesn't run on my pc.

I tried 4 games: tekken tag tournament 2, Contra Hard Corps Uprising (not a demanding game, i suppose) and King of Fighters XIII and Castlevania Symphony of the night (from PS1).

Both With OPENGL and Vulkan, the cpu is at 100% (96% for RCPS3). After the initial loadingpop up (PSU loading...), Tekken doesn't starts (black screen, after loading the proile and create the save state) adn Contra Hard Corps starts with the animated opening, but it doesn't run correctly;so I push START but there is a black screen and the game doesn't starts...
King of fighters XII starts but there are problems during the opening and during the game the fps are at 180/200!!!
Castlevania Symphony of the night after the compiling pop up, shows a black screen and my cpu run at 100%

Here my current config:
cpu: i5 4690K overclocked to 4.2Ghz
gpu: GTX 970 G1 gaming
RAM: 8 GB DDR3

My current pc isn't bad, is it possibe that my overclocked cpu isn't enough????

thank you