I've got a Core 2 Duo E8400 Wolfdale 3ghz processor, and an Asus P5N nForce SLI motherboard. I thoroughly read the post on OC'ing Core 2 Duo's and took copeous notes while doing so.
The first time I attempted this I manually OC'd the CPU by upping the FSB to 400mhz and left my video setting to 100mhz, I also made sure the ram was compatible with 400mhz, which it is.
When I rebooted the system came up fine and said it was running at 3.6ghz. After I got into windows I checked the system properties and saw that it still said it was running at 3 ghz. I thought that odd, but figured perhaps the OS was reading what the chip says it should be, rather then the actual clock. So, I ran a benchmark and found that nothing changed, the benchmark was still what it was before the OC!
So, I went into the MB settings and found that there was an automatic OC feature that came with the MB. The increments were 5,10,15, and 20%. Not knowing what kind of voltage settings the mb would opt to use, I selected 5% and tried again. When the PC was booting up, it said 3.15ghz. Once in windows (Vista btw) I ran a benchmark and saw that nothing changed.
So I went back into the automatic OC area and cranked it to 20% and tried again - Nothing changed.
So I reverted all changes back to before I started and thought I should come here and post my findings.