Just got my Asus GTX 570 Ti a few hours ago. My previous card was a GTX 580 (which recently died). Games run very smooth with the 750 Ti, even though the gpu is a little weaker. I tested some mmo games. To my surprise, when standing in a crowd of players, I did not notice any graphics lag at all. Even when the frame rate is low, I don't feel any graphics lag (except for lag due to low frame rate). My GTX 580 had a little more processing power, but rotating the view feels more responsive with the 750 Ti.
Right now, I am mining coins with cudaminer (-H 1) at 99% gpu usage and the desktop feels like cudaminer is not even running.
This guy says to use Kepler Bios Tweaker to increase power limit. Looks like voltage can be changed too.
http://cryptomining-blog.com/1014-how-to-increase-the-geforce-gtx-750-ti-power-target-limit/
I am still on stock bios.
1215 MHz coin mining
13XX MHz in games
memory at +200
fan runs quiet at constant 75%
gpu temp at 60C in games and while mining
I am a little worried about no VRM mosfet heatsink.