Variable speed OC for 8700k

[Laxmantim]

Fairly new to overclocking but I was able to get my 8700k up to 5.0GHz on my MSI Z370 Gaming M5 motherboard. It might go further but that’s plenty fast for me plus the BIOS seemingly automatically upped the vcore to 1.392v when I set the multiplier to 50 which it didn’t warn me about at all and I didn’t even discover until I went back into the bios days later.  My 2 questions are: 1.392 seems unnecessarily high even if it is watercooled, and 2 is it possible to make it behave like it did out of the box where it idles at 3.7GHz and a significantly lower voltage but turbos up to 5, because even when I set the turbo multiplier to 50 it still idles at 5GHz on the desktop with just hardware monitor open and very minimal background processes. 

[Jurrunio]

49 minutes ago, Laxmantim said:

1.392 seems unnecessarily high even if it is watercooled,

you can lower that with offset mode in CPU core voltage control. say - 0.15V will put you to about 1.242V, though better lower it at 0.02V steps and give it a test after each try.

 

51 minutes ago, Laxmantim said:

and 2 is it possible to make it behave like it did out of the box where it idles at 3.7GHz and a significantly lower voltage but turbos up to 5, because even when I set the turbo multiplier to 50 it still idles at 5GHz on the desktop with just hardware monitor open and very minimal background processes. 

Enable C-states, speedstep and EIST. I'm not sure if all of these exists in Coffee Lake though.

[Laxmantim]

Thanks for the help! Regarding the voltage I will aim to step it down closer to the 1.242 you mentioned, that seems a lot safer, you mentioned using offset mode, is that any different than just adjusting the voltage? And if so what is the benefit? Also I have speedstep and EIST enabled but I haven’t seen C-states in the bios anywhere maybe that’s what I’m missing. I’ll give that a shot and post and update in a couple hours, thanks again for your help!

[Laxmantim]

Update: couldn’t find Cstates in the bios but there was one setting (can’t remember what it was called sorry) that I changed that allowed the clock to fluctuate between 4.7-5.0 so that’s progress, however I was only able to get the VCore down to 1.355, and I had to bring the cache speed down from 4.8->4.7 because I was getting blue screens in Aida 64 stress test, I noticed the north bridge was only running at 4.7GHz before I slowed down the cache could that slower speed be contributing to instability and is it possible to adjust that? I would like to speed the cache back up but right now the system is stable at 5GHz 4.7cache and 1.355vcore