maxxx,did you try with "Turbo Boost" Disabled?
I never Enable this over 4.8GHz.
@stasio: yup, I dun enabled this when I overclock, but I needed to access the TDP/TDC settings to test. If Turbo is disabled, they are greyed out and can't access them. I want/need to get over that 4E error. Btw, know if there are other batches for the 2600k in KL?

About ET6, same boat as the rest, can't change the bclock setting. On bios F7e.