Turn off all C states except BI DIRECTIONAL PROCHOT and what DM said about Turbo ... also take a pad and paper to write down the BSOD codes when you get them......it'll be something like 0x000000124 or 0x000000xx.....these are a gold mine to get that extra few% out of your clock
Just a small sample of the information available to you with BSOD codes.....
BSOD codes:
BSOD codes for overclocking
0x101 = increase vcore
0x124 = increase/decrease vcore or QPI/VTT...have to test to see which one it is
0x0A = unstable RAM/IMC, increase QPI first, if that doesn't work increase vcore
0x1E = increase vcore
0x3B = increase vcore
0x3D = increase vcore
0xD1 = QPI/VTT, increase/decrease as necessary
0x9C = QPI/VTT most likely, but increasing vcore has helped in some instances
0x50 = RAM timings/Frequency or uncore multi unstable, increase RAM voltage or adjust QPI/VTT, or lower uncore if you're higher than 2x
0x109 = Not enough or too Much memory voltage
0x116 = Low IOH (NB) voltage, GPU issue (most common when running multi-GPU/overclocking GPU)
This was taken off an excellent tutorial .... here! ....
http://www.overclock.net/intel-cpus/538439-guide-overclocking-core-i7-920-930-a.html NOTE! The above link and advise is for the i7-920/30/50 and 60.....do not take at face value for the 2500 and 2600......additional research is advised.....they are just supplied as a guide line as BSOD codes should be relevant for the i7 architecture
ENJOY!
Aussie Allan