I managed to screw up keyboard.
Had to do system restore in order to get it working again.
Logitech drivers haven't been updated since 08/30/2010. Looks like it's same with saitek drivers (only RAT 5 is relatively new, 2011).
But I'm pretty sure that Logitech G940 is not the one causing problems, because I got it few weeks ago and I had had problems with BSOD way before then.
We'll see tomorrow if BSOD still occurs while playing games.
And one more thing. Do you know why I don't get blue screen? PC restarts but won't boot (instead I get 6 beeps) and I have to turn it off by pressing power button and then I will be able to boot normally. (This only happens when BSOD occurs during playing games, with Driver Verifier I get blue screen and I'm able to boot normally)