i5 8600k strange vcore behaviour with LLC applied

SaTrOx · 15 Oct 2017 at 21:20

Hi guys im trying to OC my cpu and im having a very hard time getting it to stabilise at 4.8ghz

Ive got manual vcore override set to manual at 1.3v cpuz reports 1.296 - 1.28 (it doesnt stay in place)

When i start prime95 blend test vcore drops to 1.28 wih LLC on auto and stays there.

Now the strange part when i set LLC to level 4 (my board has levels from 0 to 7) and cpu current capability to 140% vcore under load drops to 1.24 wth is going on here?

I have tested this on old bios version and new same behaviour on both of them.

My pc specs :

i5 8600k

Asus Z370 Gaming plus

8GB corsair vengeance LPX 2400mhz

Corsair CS750M

GTX 1070.

benjii · 16 Oct 2017 at 00:43

Load Line Calibration (LLC) is designed to prevent vdroop, which you are seeing when your voltage drops under load. When you had LLC on auto, it was obviously higher than level 4. Keep increasing LLC 1 level at a time and testing it under load to see what the voltage does. At one of the levels level, vdroop will turn into vboost, where your voltage increases under load. Hopefully you can find a happy medium, if you can't, don't forget you can use voltage offsets. For example, my 6700k is set at 1.35v in bios and achieves 1.35v on desktop, under load. I actually have vboost, as LLC is at level 6, but I set a -0.035v offset to counter it.

SaTrOx · 17 Oct 2017 at 10:21

I have LLC set to level 7 and vcore still drops by a lot during stress test :

1.31 in bios cpuz reports 1.296 same with hwinfo64
Under load at llc 7 vcore drops to 1.264 sometimes for couple seconds to 1.24

All C states disabled, asus mce off and all that at merely 4.8ghz oc.

At these setting my cores are not dropping under p95 blend test, but still theres something off with the voltage fluctuating so much

danny77 · 20 Oct 2017 at 05:53

Not sure if its the same on your board but apparently llc doesn't work on the asus strix z370 boards ?

https://www.youtube.com/watch?v=hCAQpvFhiUs

benjii · 20 Oct 2017 at 12:18

danny77 said:
Not sure if its the same on your board but apparently llc doesn't work on the asus strix z370 boards ?

https://www.youtube.com/watch?v=hCAQpvFhiUs

Something strange is happening, that's for sure. OP saw no difference between level 4 and level 7, that's not right.

Are you using the latest bios?

SaTrOx · 20 Oct 2017 at 15:20

I already know whats happening, spoke with asus rep on forums and the conclusion is dont buy any of their "low end" boards as they wont be getting any kind of support regarding voltage, due to poor vrm design.

quote of asus rep :

"No. The capable Strix models and Prime models have been updated. The ROG Maximus boards didn't have this level of vdroop so don't need the 'fix'. Models outside that are budget class/low-end, so need a given level of Vdroop to compliment the capabilities of their power solution. There is nothing surprising about this and it has nothing to do with broken or not fully functional."

Basically buy our expensive boards if you want support.

I have arranged return of this board and i will be taking asrock k6 z370 it already received bios update regarding llc.

Ive got to add that on this board even intel speedsptep and turbo mode does not work correctly, with everything in bios set to default on a desktop cpu sits at 1.2vcore and does not throttle down, but asus doesnt seem to bothered about it as it is "low end" in their eyes.