The three keyboards I listed in the title (i.e., the CM XT-Stealth, the CM Quickfire XT and the CM Quickfire Rapid) work in both PS/2 and USB mode. They also all feature NKRO (N-key rollover) in PS/2 mode. My question is: what are their KRO's (key rollover's) in USB mode? P.S.: Let me just "briefly" explain why I asked the above question: I play a fighting game called Grand Chase, where USB mode seems to be better suited for certain combos, in which one has to hit multiple keys at once: due to the PS/2 mode's precision, if you try to hit multiple keys at once, say, D and S, the keyboard may notice, say, you hit D just a little bit before S, so that you fail the combo. On the other hand, I don't want a USB-only keyboard, because I play another game (a rhythm game called Stepmania), where the more precision the keyboard offers, the better, so that a PS/2 keyboard is superior for this game. So a keyboard that works both as USB and PS/2 would be perfect for me, but it wouldn't be possible to play on a 2KRO keyboard, hence the question. (I think something like 6KRO would suffice, though.) P.P.S.: I actually have only tested three (membrane) keyboards I have at home, two of which are USB-only and one of which is PS/2-only, and then extrapolated what I observed to USB and PS/2 keyboards in general. I might be wrong, but my theory seems to make sense and seems to be consistent with the information I've gathered by surfing the internet. Thanks!