Adaptive voltage accuracy - 8700 non K, Z370-G

[Hammond]

Hello,

I am here to ask you for an advice. I have new PC - Asus ROG Strix z370-G gaming, Intel i7 8700 (non K), 2x HyperX Predator DDR4 3000 mhz, so far no dedicated GPU because I waiting for new Nvidia models, Samsung Evo 970 500GB, PSU Seasonic Focus Plus 550wk, Scythe Mugen 5 rev. B cooler

Problem is that auto CPU voltage is extremely high. it hits 1.4v in load (I mean real voltage read by hwmonitor and gpu-z not VID). First I tried to change SVID behavior to best case scenario. But I dont have SVID behavior option in my bios. Is this normal for z370-g motherboard and 8700 non K? Also I have missing AVX offset settings in bios.

So I decided to undervolt it manually. Try 1.2v and it looks stable after some Prime, OCCT and cinebench testing. So I decided keep this value for now and use it (maybe in future I could test lower settings, but for now I am OK with 1.2v). Manually set 1.2v with everything in bios set to default show exact 1.2v in idle/load in hwmonitor and gpu-z. So then I went to bios and wanted to change voltage to adaptive. I have done this: Check if SVID support is enabled, than change voltage to adaptive and set Additional turbo voltage to 1.2. This settings resulted in strange behavior and voltage was not even close to 1.2 in load. With this settings the load voltage was fluctuating at 1.1-1.8 but often really low. So I set AC/DC load lines to 0.01 due to Rajas tutorial. Not much difference after that. So I also try to set LLC from auto to 5 and 6. It fixed big vdroop but now voltage is:

1.184-1.215 in multicore cinebench
Prime 29.4 - 1.248
Prime 26.6 - 1.184 - 1.215
ffmpeg conversion (most power consuming test I have) - 1.232

I finds that single core test tends to push more vcore about 1.248 and multicore tests lower closer to set 1.2. Also AVX tests set more vcore which is I supposed normal. But even with AC/DC loadlines set to 0.01?

So as summary: Adaptive voltage set to 1.2 with AC/DC load line 0.01 and LLC 5 or 6 resulting in 1.18-2.48. which is big deviation from set 1.2. I have latest bios ver. 1002.

Thanks for any advice. Have a nice day.

[Menthol]

This doesn't look like a big variation to me, at least not from my experience, 1.18 to 1.248, a load draws more current, voltage varies to compensate, there is always a percentage of fluctuation, There is also a margin of error in software that should be taken into account which is near impossible to do and unless you compare with a DVM or silly scope have no idea how inaccurate software actually is

[Hammond]

Hi, Thx for you answer. It is ok then 🙂 Do you think it is ok to use manual LLC instead of auto when adaptive voltage is used?

Can you please tell me difference between AC/DC load lines settings and SVID behavior? Because I missing SVID behavior options on my mobo. It is ok for this mobo to not to have SVID behavior and AVX offset settings?

[Menthol]

Setting AC/DC to 0.01 basically does the same thing as the best case SVID behavior setting, yes you can set LLC manually when using adaptive voltage control, I use LLC 5 or 6 myself

[Hammond]

Thank you very much Menthol 🙂

[Menthol]

Your welcome Hammond