I've always kept with the rule of thumb to ONLY go up to maybe 115% of stock speed, it's unlikely that most CPUs in a batch will exceed that anyway. Although I've never overclocked... well, except I overclocked my 286 by replacing the crystal oscillator! I sped along at 16mhz when all the pansies were... well, actually this was 2002 so they probably had faster PCs, but my point remains.