Thank you Pol!
that's what I did , but I cannot figure out what gfx card is on duty when I play WOFF or WOTR...only the fact that I never have more than 40 FPS in both games when flying an free flight with everything maxed out and systematic CTD when launching both games with Nvidia gfx set on global settings inNvidia control panel ...and you're right ,that would be sad to play on an intel MOBO graphics card :-) !!