I'm running a 2.66GHz Bloomfield (D0) Intel Core i7 at 3.8GHz. System is 2.5yrs old and has bluescreened five times in its entire life, all while shutting down applying Windows updates.
I stalked the Overclockers forums for a couple of months selecting a good board for clocking (Asus P6T Deluxe V2). I chose a target speed, based on what people were thinking as extreme for air cooling. At the time, that was around 4.2GHz, so I decided to knock 10% off that and go for 3.8GHz.
I calculated the BCLK required, and used the Asus auto overclock to configure the board. Then, over a period of around four days, I adjusted voltages using the Asus Windows app, bringing them down and down. Got from about 1.4v to 1.18v. It's all about increments, baby steps.
I was using CoreTemp and Prime95 to test. As the system becomes more stable, it goes from a simple hang, to bluescreening, to dropping threads in Prime95.
My board barfed its BIOS config in October, necessitating a total rebuild. Before I reclocked it I noticed it was really sluggish, so although I'm not sure I hit the processor that hard in daily use, I definitely noticed when it wasn't clocked.
My advice above and beyond that which has already been said, is to buy a board which the overclocking community. They usually have get-out-of-jail-free features such as vCore protection, default clocking, and the ability to save BIOS configs. Many times my board POSTed with "Overclock failed. Return to default settings?" rather than lunching my kit.
(For more on my system, search this forum for "Photomonster")
