Herc08 :
Well first off, it's not safe, nor recommended to overclock a non-K CPU. So if it fries or gets messed up, it will not be covered by warranty.
It was not designed to be overclocked. I get it, it worked for a few days, and you're lucky that it didn't fry.
Who said that? Its just as safe to overclock a non k cpu using the BLCK method as it would be a k cpu, assuming voltages are in check and you keep it cool. I dont think there is anything special about the k cpu's other than intel unlocking the multiplier, a 6500 from my understanding is the same as a 6600k minus the unlocked multiplier and higher stock clock speed. And if you fry a K cpu due to overvolting the hell out of it or something, I doubt your going to be covered by warranty either. Where are you getting this info about non k cpus?
As for the OP's question, I have no idea BLCK overcloking is much harder to get stable than multiplier overcloking, as it changes more than just the clock of the cpu. What are your memory speeds at? Turning up the base clock will increse memory speeds as well as cpu speeds.
Honestly i'm surprised you are even still able to do this at all, do you have an old bios? I thought intel locked this down shortly after launch.