I bought a delidded 3770k and the previous owner had it on 4.8ghz at 1.39v with offset on an asrock z77 board(llc second to highest, cpu pll 1.50 everything else he had it on auto).
My board is an asus p8z77 vlk and so far i can only get it stable up to 4.6ghz, for 4.7 i need 1.39-1.40 vcore and prime95 still gives me errors. the 27.7 version runs a lot longer before an error is found and the 28.5 version gives me soon some fatal error rounding 0.5 message. By the way 1 worker from the 8 workers gets stuck at test 1. My cpu pll cant go below 1.80 by the way. My ram is corsair vengeance 16gb at 1.5v, i'm using xmp profile for that.

What you guys recommend me to do, is it my board that doesn't let my cpu be stable even at 4.7 not to think about 4.8 lol.

Another thing about the offset, on my i5 2500k at 4.8ghz my power plan was at high and all i had to do for speedstep to work was disable the c states and enable the c1. On the i7 i need to have my power plan to balanced for the speedstep to work. By the way so far i was testing the i7 with manual voltage and power plan was on high.

That's not a great motherboard for overclocking. It only has 4 phases for the CPU power. You need something that has around 12 phases or more to get a solid overclock, like the P8Z77-V PRO.

Thanks for the advices!
I recently followed to the letter the guide from this video
https://www.youtube.com/w...KwGSLr5W-w&index=2
and was able to get a stable overclock of 4.7ghz at 1.395 vcore. I was surprised to find out things like internal pll overvoltage enabled, spread spectrum disabled, dram voltage raised a little, etc mattered a lot to have a 4.7ghz overclock stable, where with my i5 2500k at 4.8 none of that was necessary.

bob16314
Good job..A little more offset/Vcore should get you 4.8GHz if that's your goal, although in reality you probably won't notice any difference between 4.7GHz and 4.8GHz.
 
Having Internal PLL Overvoltage enabled can cause not resuming from sleep and hibernate problems, it's a known issue, I have it when it's enabled (which I currently don't), just a heads up.  

I tried for 4.8 but prime95 was giving me errors all the way up to 1.45v, i was told to be on the safe side to never exceed 1.45v, so far i have no problems with pll overvoltage enabled but i will let you guys know if i come across any.
 
Another interesting thing i noticed with prime95 at 4.7ghz any voltage below 1.395v and any voltage above 1.395v will cause one worker to get stuck at test 1 while all others keep going through countless tests, there's no error just 1 worker stays at the test 1 forever. 1.395v was the sweet spot to have all the workers moving at almost equal speed.