Asus Z170 Power Limit 1 and Power Limit 2

ron_dv · Feb 4, 2016

Can someone help me better understand what power limit 1 and power limit 2 do in the bios? My motherboard is an Asus Z170-AR and cpu is an i5-6600k.

In the bios, Power limit 1 can be configured to be on [Auto] or [1-127], is this in watts? If so, should I set it to 91 W to match my cpu's TDP? And Power limit 2 can be configure to be on [Auto] or [1-4095] is this also in watts!? How should I set this? Asus is not really clear on their explanations and how to set them properly.

I just want some sort of protection while I play around and get familiarize with overclocking.

Thanks.

blazorthon · Feb 4, 2016

http://dlcdnet.asus.com/pub/ASUS/mb/LGA1151/Z170-AR/E10395_Z170-AR_UM_WEB.pdf

Page 80 explains this a bit. These values are measurements of time, not power. You couldn't pull 4000W even if you wanted to XD

ron_dv · Feb 4, 2016

Alright, I guess what was confusing me was Intel's definition of power limit 1 and 2. They are as follows;
*Power Limit 1(PL1): A threshold for average power that will not exceed - recommend to set to equal TDP. PL1 should not be set higher than thermal solution cooling limits.
*Power Limit 2(PL2): A threshold that if exceeded, the PL2 rapid power limiting algorithms will attempt to limit the spike above PL2.

Intel is obviously referring to power here.

Also, in Intel XTU both Turbo Boost Power Max(PL1 Limit) and Turbo Boost Short Power Max(PL2 Limit) have a value of 4095 Watts, this is the same upper limit values Asus is using in its Long and Short Duration Package Power Limit. The only one using the unit Seconds is the Turbo Boost Power Time(PL1 Time) with a value of 8 seconds.

Thanks for your response and the link to the manual.

blazorthon :

Leaps-from-Shadows · Feb 4, 2016

This is the way I understand it:

Long Duration is what you might call the "safe long term wattage" for your CPU.
Short Duration is is the wattage you don't want your CPU to exceed for very long.
Time Window is the time, in seconds, that your CPU can be over the Long Duration wattage before it auto-throttles to keep it below the Long Duration wattage.

I have my safe wattage set to 150.
I have my do not exceed wattage set to 160.
I have my time window set to 127.
I have very good custom liquid cooling. You don't want the settings this high with air cooling or an AIO.

With those settings, my CPU can be below 149W forever, but once it exceeds 150W for 127 seconds, it will auto-throttle back down below 150W. If it exceeds 160, it will auto-throttle immediately.

According to HWinfo64, my CPU has exceeded 150W when I was investigating the maximum overclock. Since then it hasn't, as I had to settle for a lower overclock for stability. Most good monitoring programs will tell you what your CPU's wattage is in real time.

You can set Long Duration to 110 initially, and then see what your actual wattage is while gaming overclocked and over-volted.
Set the Time Window to 127.
Short Duration defaults to Long Duration x1.25. Might as well just leave it at Auto.

Adjust the Long Duration as necessary. Leave the Time Window at 127 -- it won't hurt your CPU to spend that amount of time above the LD.

Note that there is no real "safe wattage" for a CPU. I just can't think of a better term to explain the LD.

ron_dv · Feb 5, 2016

Hey Leaps, thanks for this great explanation, very informative. Now to follow your suggestions, I will set the Long Duration Package Power Limit to 110 W, leave the Short Duration Package Power Limit in Auto, and set the Power Package Time Window to 127 seconds. I think I got it now.

Thanks again.

Leaps-from-Shadows :

This is the way I understand it:

Long Duration is what you might call the "safe long term wattage" for your CPU.
Short Duration is is the wattage you don't want your CPU to exceed for very long.
Time Window is the time, in seconds, that your CPU can be over the Long Duration wattage before it auto-throttles to keep it below the Long Duration wattage.

I have my safe wattage set to 150.
I have my do not exceed wattage set to 160.
I have my time window set to 127.
I have very good custom liquid cooling. You don't want the settings this high with air cooling or an AIO.

With those settings, my CPU can be below 149W forever, but once it exceeds 150W for 127 seconds, it will auto-throttle back down below 150W. If it exceeds 160, it will auto-throttle immediately.

According to HWinfo64, my CPU has exceeded 150W when I was investigating the maximum overclock. Since then it hasn't, as I had to settle for a lower overclock for stability. Most good monitoring programs will tell you what your CPU's wattage is in real time.

You can set Long Duration to 110 initially, and then see what your actual wattage is while gaming overclocked and over-volted.
Set the Time Window to 127.
Short Duration defaults to Long Duration x1.25. Might as well just leave it at Auto.

Adjust the Long Duration as necessary. Leave the Time Window at 127 -- it won't hurt your CPU to spend that amount of time above the LD.

Note that there is no real "safe wattage" for a CPU. I just can't think of a better term to explain the LD.

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