If you're thinking about overclocking and going low volt with
QuickClock, install
jRummy's Overclock and set the ULV (lowest voltage settings), starting low and slowly working your way up. Try one speed for awhile, maybe play a game. My wife can crash a week-long, stable setting playing
Jewels, so if you think it's stable, play that for 30 minutes.
When you find a setting that crashes your phone, you probably need to drop back 1 or 2 settings. Run that for a week. If you get any goofiness you didn't have before, drop it back a notch. QuickClock has a new stress test to check for lags and
SetCpu also has one. I crashed quickly at 1400/ULV, had 1350 for a week (dialer crashed), dropped it to 1300 for two more and ended up at 1250.
After at least a week of no problems, then think about Quickclock. I have found the auto calibration to be too aggressive and you'll probably want to increase that by one or two in practice.
Bear in mind you might want to go into airplane mode, reboot, and let the phone sit idle for a couple minutes before doing a stress test. That way any background processes will settle down. I found that I had about 10 lags in 300 seconds, even at the stock setting (no OC).