Actually, you can hear the audio slowdown (without stuttering and with pitch-bending) when the Framelimit is higher than your FPS (but not too much). You can test it out for yourself (just create a GPU bottleneck in a game of your choice). TimeSplitters 2 (the Start Screen) runs 48 whenever I boost the IR to 3x or greater, and with a Framelimit of 55, I still hear no stutter and get the weird pitch-shifting. Same for SMG2 (3x IR + 4xSSAA kills my GTX 550 Ti 
) Runs 27 in places, but a Framelimit of 30 gives no stuttering (35 does, however).
) Runs 27 in places, but a Framelimit of 30 gives no stuttering (35 does, however).