You shouldn't be changing the BCLK any, with a 4570 even if you don't have the K version, you're allowed 4X multi bins (so you can raise your turbo core by 4X) which would give you an even 4Ghz
It's a 4570 not a 4670K.
Why did you get a 4570 instead of a 4670K if you wanted to overclock... ?