Want to OC my 6600 to 4Ghz but can seem to find right combo

Good luck on this. I've read a few of those posts too. I can't get mine past 3.2 with any stability. On some of the boards I've been to, it seems the 4g mark is something you can get with dry-ice cooling and by modding your motherboard voltage regulator system, but not anything that you'd want to keep it set at to play games. Others say you can run it up to 3.6 stable, but when I get over about 3.25 it starts getting flaky on me. Even after upgrading my video card to an 8800gtx, I can't do anything better. Some say it's the luck of the draw on the processor that you buy, I'm thinking it may also, in part, be related to the memory/motherboard configuration. I have OCZ 6400 memory, but unless I crank the voltage up on it, I can't even stay stable at 3.2. If I drop the voltage as much as .05 it stops responding after a while playing.

Interesting, I've been reluctant to push my memory that hard, but as I mentioned, the memory did seem to be a big factor in my limitations. I might take the plunge, since I have some highly rated memory. I'm already in the red at 2.1v maybe I can push it a bit more. Still, I'm not sure that the benefit would be worth it, but it will be interesting to see if it allows me to go to the 3.4 range, as you did, and still be stable. Since I'm water-cooled, it makes things a little safer, but the memory is still on air. I've got a Tai-chi case though, which has incredible ventilation and passive vent cooling system on it, so at least I don't have heat as a major issue. Thanks for re-posting your results. I'll let you know if I find similar results on mine.