[SOLVED] 10850K MSI Z490 Tomahawk Undervolting

[Nighthawk117]

Hi guys,

I have a Z490 Tomahawk and 10850K, I've been playing around with undervolting in the form of a negative vcore offset.

Some background, I don't use turbo boost because I prefer a cooler and quieter machine. I manually set the CPU multiplier to 45.

Today I've been experimenting with undervolts with the CPU at 4.5Ghz and 4.8Ghz.

Everything is on auto except I have set CPU Core/GT Voltage Mode = Offset Mode and the system is currently running at 4.5Ghz with a -0.03v offset.

So far I've only run Cinebench R23, I will run proper stress tests later. Right now my max vcore has gone from 1.23v to 1.198v on HWMonitor after running
Cinebench.

A few question's I hope you can help me with:

1) 10850K owners, what undervolts were you able to achieve, at stock preferably or whatever frequency you have.

2) Any reason why core VID's would be slightly higher in offset mode compared to stock configuration?

3) I notice the package power is actually slightly higher with the undervolt despite vcore showing being lower.
Max package at 4.5Ghz auto was 142.97W. In offset mode with -0.03v it was 144.38W. Temps were 2C lower in offset mode, 66C instead of 68C.

Thanks

 

[uWebb429]

I don't use turbo boost

Yes you do. The 10850K has a default multiplier of 36. Any time you are using a multiplier higher than that, Intel Turbo Boost has to be enabled within the processor. Some Gigabyte motherboards used to have BIOS settings that can be misleading. They would give you a fake option in the bios to disable turbo boost but then the board would turn it right back on after you pressed OK.

With turbo boost enabled, it is still possible to run the 10850K at a fixed frequency regardless of load. Turbo boost and a fixed frequency are two different things. Here is my 10850K running all cores at 5000 MHz when idle. Temperatures and power consumption are low because the low power C states are enabled.

The default voltage for the 10850K tends to be too high. There is lots of room to undervolt these CPUs. I can easily run Cinebench at 4.5 GHz with the VCore voltage as reported by HWiNFO at 1.101V. You can probably run a -100 mV (-0.100V) undervolt and still be 100% stable.

I need 1.190V to run Cinebench stable at 4.9 GHz. At default bios settings, this CPU would probably be getting 1.30V.

I would not worry too much about VID voltage. It does not mean too much. Actual VCore voltage going to the processor is a much more important number to watch.

The power consumption data that Intel CPUs report is a calculated estimation. It is not measured power consumption so I would not worry too much about this number either. The VID voltage value is used to calculate estimated power consumption so do not put too much faith in either number. Do not use it to make any comparisons to other 10850K CPUs. I would not use this data for any purpose.

Instead of slowing your CPU down, it might be a better idea to adjust the turbo power limits. The PL1 and PL2 power limits control how much power these CPUs consume short term and long term. I use ThrottleStop so I can easily adjust these power limits at any time without needing to reboot. You can also adjust the maximum CPU speed at any time without needing to reboot. It is a very useful program and was specifically written to fine tune the 10850K. It gives you access to the two Clamp options within the CPU so you can clamp power consumption to whatever you like. The bios for most motherboards does not let you toggle Clamp on or off. Intel XTU also lacks this important option.

 

[Nighthawk117]

Hi, what I mean is I've disabled the three bios turbo boost settings, Intel Turbo Boost Technology, Intel Turbo Boost Max Technology 3.0 and Intel Thermal Velocity Boost and set the multiplier myself manually. How that works behind the scenes though I wouldn't know, I'll take your word for it on that.

I am still using dynamic frequency, voltage and the C states. The reason I ask about the VID is because they don't seem to behave quite the same since changing to offset mode. Also I don't get vcore breakdown per core, I just know the max vcore.

I see you have an Asus board, they have some more fancy overclocking stuff don't they? I saw a video where they could set different voltages per CPU ratio or something. I don't think I have anything like that. With what your doing there, are you applying a negative offset across the board. So like the voltage offset at low idle frequency is the same as it is at max frequency?

The reason I don't use power limits is because even with a small number of cores at their max clock speeds it gets quite noisy.

I tried undervolting on my previous CPU system, and I think the idle voltage got too low that it wasn't stable. Is this something I should be concerned about?

Can I ask what CPU cooler you are using?

 

[uWebb429]

what CPU cooler you are using?

I am using the Corsair H115i Pro XT. I installed it more than a year ago with the pre-applied paste and I have never needed to look at it since then.
https://www.corsair.com/ca/en/Categ...oling/iCUE-RGB-PRO-XT-Coolers/p/CW-9060044-WW

I am still using dynamic frequency

Look at the first screenshot I posted with the CPU running at 5000 MHz when it is idle. The VID voltage is high but power consumption and most importantly, the CPU core temperatures are very low. The C states are reducing idle power consumption and voltage. There is no real need to slow these CPUs down.

When a core enters the low power C7 state, it is disconnected from the voltage rail and it is disconnected from the internal clock. That means the core is sitting there basically dormant at 0 MHz and 0 volts. Find a multiplier and speed you like and lock it to that value so it runs the same speed whether idle or at full load. Running a fixed CPU speed will allow you to undervolt further without any stability issues. A CPU will need more voltage to run reliably if you allow it to vary its speed.

I don't get vcore breakdown per core

All active cores are running at the same speed and are being fed the exact same voltage. You only need to look at one voltage number, the VCore voltage. Monitoring software can wake up idle cores once every second and ask the core to report its VID voltage but whatever number that is reported is meaningless if the core was actually at 0 V for 99% of that monitoring period. Forget about VID voltage.

are you applying a negative offset across the board

I used to use a negative offset voltage but I found that lowering the IA AC / DC Load Line values to 0.25 works best for me. This is a different way to reduce the voltage. This method seems to reduce the idle voltage less compared to using an offset voltage so I get better stability using this method. Now that I lock my CPU to a fixed frequency, this no longer matters. It is way easier to come up with a stable setting when you only have to worry about one CPU speed and one voltage.

I tried undervolting on my previous CPU system, and I think the idle voltage got too low that it wasn't stable.

That is a common problem when using an offset voltage that reduces voltage across the entire voltage curve. Use a fixed frequency and this problem is gone. You will be able to undervolt more and still be 100% stable.

Asus board

This board allows you to adjust the voltage at different speeds but I never use that feature. I do not want my CPU to slow down. I typically run it so whenever a core is active, it is running at 5000 MHz. When a core has nothing to do, it is inactive and goes into C7 where it is at 0 MHz. Modern Intel CPUs can enter and exit the C states very quickly and directly so there is no need for all of the intermediate multipliers. These CPUs can have all of the cores spending 99% of their time in C7 at 0 MHz. When a core has something to do, best to run it at full speed so it can get the task done quickly. That allows the cores to spend a bigger percentage of time idle in C7. A fast CPU is a win win situation.

even with a small number of cores at their max clock speeds it gets quite noisy.

With 4 cores fully loaded running a stress test, power consumption is at 80W and the cooler I am using is almost silent. Temperatures are low so I turned off all of the case fans. They are not necessary. Have a look into adjusting the CPU fan curve. Intel CPUs can run reliably at high temperatures so reduce the fan noise pollution.

 

[Nighthawk117]

That's interesting what you say about using fixed speeds, I'll give that some thought. Your cooler is similar in capacity to mine, I'm using a 240mm Asus LC240. I know Intel CPU's can technically run hot, it just upsets my OCD. I'd prefer to keep temps below 70C. Thanks for the detailed reply.