MSI Z370I Gaming Pro Carbon AC with 8700K Overclock Issue

[Tobias]

Morning Guys,

I assembled the following over the weekend:
MSI Z370I ITX
8700K
16GB Corsair Platinum (2x8)
MSI 1080ti
EVGA 750W G3 SuperNova
Noctua D14

In short:
Run prime95, monitoring temps with "core temp". After between 5 and 10 seconds, the clock speed drops first to 4.2G, then 3.7G, then 3.5G and looks like either thermal or voltage throttling. At the point before throttling the max core temp reported by "core temp" was 74 degrees C.

I have disabled step, c1e, etc. I can see that during idle, the clock never reduces so I think I have got that nailed. Before I disabled these, the clock would drop to <1G. I have also disabled turbo.

I have taken manual control over cpu voltage and set it to 1.25V.

RAM is dominator platinum designed for xmp 2.0, which I have set and forget. No issues with the RAM as far as I can tell.

I have a few thoughts:
1: Could the fact I am running an itx motherboard limit my overclock potential? Of all the z370 ITX motherboards, this one has the most VRMs (7 or 8). I have no way to monitor the VRMs short of stick a thermocouple on them (which I will do if you think its beneficial).
2: Have I overlooked anything? Will this processor de-clock under a situation I am unfamiliar with? My last intel processor was a gen 4.
3: How can I tell if the voltage is my limitation, rather than heat? My system seems stable, has not crashed at all.
4: In the BIOS there are a couple of settings to firstly do with short term power draw, plus long term power draw. These are both set to auto. There is not much info on these, so I don't know how I should configure them. Are either of these likely to be my problem?

I am not sure if perhaps my motherboard has a fault? I can use the PC fine, play a game etc, just during stress testing the processor complains. I am inclined to think it is the motherboard and not the CPU as the system is otherwise stable.

Please share your thoughts. I will approach MSI directly if required. Thanks.

 

[Danny75]

BIOS updated?

Does the decrease occur in other benchmark/stress programs?

Does CPU-Z confirm the decrease reported by CoreTemp?

1: Could the fact I am running an itx motherboard limit my overclock potential? Of all the z370 ITX motherboards, this one has the most VRMs (7 or 8). I have no way to monitor the VRMs short of stick a thermocouple on them (which I will do if you think its beneficial).

Possible but what you describe does not sound normal.

2: Have I overlooked anything? Will this processor de-clock under a situation I am unfamiliar with? My last intel processor was a gen 4.

Coffee Lake has an AVX offset, have a read up on that, could be for some reason it's set very low.

4: In the BIOS there are a couple of settings to firstly do with short term power draw, plus long term power draw. These are both set to auto. There is not much info on these, so I don't know how I should configure them. Are either of these likely to be my problem?

Does your BIOS have auto-overclock option? If you set an auto, save and reboot, and then take a look at those settings you mention, it may show values other than Auto. Could write them down if so, and apply them to your own custom overclock settings.

 

[Tobias]

BIOS updated yes.

Which other stress test would you like me to try? I went with prime as I thought it was the most severe. I will try any others you suggest.

I haven't correlated the decrease between CPUZ and core temp; I will do that.

I was using an AVX offset of 4 so even when I ran a test at 4.5G accross all cores turbo disabled, this would have prime running at 4.1 I believe. Should I consider going for an AVX offset even higher, say 6?

I will look into auto overclock features. I think all these z370 boards have something along those lines. But it was my understanding that auto is pretty bad in terms of voltage control; setting a lot higher than desired. Wouldn't a higher voltage just mean if I am indeed hitting a thermal throttle, I will now hit it sooner with auto? I guess I could try it, it would take less than 5 minutes.

Thanks for the suggestions.

 

[Danny75]

BIOS updated yes.

Which other stress test would you like me to try? I went with prime as I thought it was the most severe. I will try any others you suggest.

Cinebench, Realbench (particularly the Handbrake test, believe it's the third), Intel Burn Test (or Intel Xtreme Tuning Utility test).

I was using an AVX offset of 4 so even when I ran a test at 4.5G accross all cores turbo disabled, this would have prime running at 4.1 I believe. Should I consider going for an AVX offset even higher, say 6?

Wouldn't know. I'm on 4th Gen myself, just aware of that AVX feature with the new 8th Gen.

I will look into auto overclock features. I think all these z370 boards have something along those lines. But it was my understanding that auto is pretty bad in terms of voltage control; setting a lot higher than desired. Wouldn't a higher voltage just mean if I am indeed hitting a thermal throttle, I will now hit it sooner with auto? I guess I could try it, it would take less than 5 minutes.

This is correct, only on rare occasions does an auto-overclock not set higher voltages than needed. But all you're going to do is set it and check the Short and Long Power Draw values, not have an auto-overclock running 24/7. You can set your own voltages afterwards, but have the Short and Long Draws the same to make sure it's not throttling.

Thanks for the suggestions.

No problem. Pretty sure someone who's on the same platform will come along and be able to help. Just thought I'd share some things to try meantime.

 

[Tobias]

I found this written for the MSI motherboard and 8700K:

https://www.msi.com/blog/LLC_what_i...motherboards_the_best_choice_for_overclocking

I will play with LLC later too.

 

[Tobias]

I had to set mode 2 in LLC to prevent droop, but the actual issue was in the BIOS. Low and high power settings. I noticed in XTU that I was hitting the "power throttle". The BIOS running auto for low and high power figures would throttle anything that looked suspicious, i.e. my overclock. Upping these to 130W seemed to do the trick and it no longer throttles!

Thanks

 

[Danny75]

I had to set mode 2 in LLC to prevent droop, but the actual issue was in the BIOS. Low and high power settings. I noticed in XTU that I was hitting the "power throttle". The BIOS running auto for low and high power figures would throttle anything that looked suspicious, i.e. my overclock. Upping these to 130W seemed to do the trick and it no longer throttles!

Thanks

Nice.

 

[Tobias]

Update: Not regarding the issue, but the overclock.

The CPU seems totally stable at 5.0 so I started playing with voltages. To find a sweetspot I then went to 4.9, then to 4.8 each time playing with voltages. At 4.8G, I run override mode with 1.18 core voltage and it passes stress tests absolutely fine. Thats really low! I wonder what voltages other people have achieved with 4.8G? Usually people look to get the highest clock, but I am tempted to continue running this rather than boost the voltage to hit 5.0!