Power Consumption

The nature of reporting processor power consumption has become, in part, a dystopian nightmare. Historically the peak power consumption of a processor, as purchased, is given by its Thermal Design Power (TDP, or PL1). For many markets, such as embedded processors, that value of TDP still signifies the peak power consumption. For the processors we test at AnandTech, either desktop, notebook, or enterprise, this is not always the case.

Modern high performance processors implement a feature called Turbo. This allows, usually for a limited time, a processor to go beyond its rated frequency. Exactly how far the processor goes depends on a few factors, such as the Turbo Power Limit (PL2), whether the peak frequency is hard coded, the thermals, and the power delivery. Turbo can sometimes be very aggressive, allowing power values 2.5x above the rated TDP.

AMD and Intel have different definitions for TDP, but are broadly speaking applied the same. The difference comes to turbo modes, turbo limits, turbo budgets, and how the processors manage that power balance. These topics are 10000-12000 word articles in their own right, and we’ve got a few articles worth reading on the topic.

In simple terms, processor manufacturers only ever guarantee two values which are tied together - when all cores are running at base frequency, the processor should be running at or below the TDP rating. All turbo modes and power modes above that are not covered by warranty. Intel kind of screwed this up with the Tiger Lake launch in September 2020, by refusing to define a TDP rating for its new processors, instead going for a range. Obfuscation like this is a frustrating endeavor for press and end-users alike.

However, for our tests in this review, we measure the power consumption of the processor in a variety of different scenarios. These include full peak AVX workflows, a loaded rendered test, and others as appropriate. These tests are done as comparative models. We also note the peak power recorded in any of our tests.

First up is our loaded rendered test, designed to peak out at max power.

In this test the 3995WX with only 64 threads actually uses slightly less power, given that one thread per core doesn’t keep everything active. Despite this, the 64C/64T benchmark result is ~16000 points, compared to ~12600 points when all 128 threads are enabled. Also in this chart we see that the 3955WX with only sixteen cores hovers around the 212W mark.

The second test is from y-Cruncher, which is our AVX2/AVX512 workload. This also has some memory requirements, which can lead to periodic cycling with systems that have lower memory bandwidth per core options.

Both of the 3995WX configurations perform similarly, while the 3975WX has more variability as it requests data from memory causing the cores to idle slightly. The 3955WX peaks around 250W this time.

For peak power, we report the highest value observed from any of our benchmark tests.

(0-0) Peak Power

As with most AMD processors, there is a total package power tracking value, and for Threadripper Pro that is the same as the TDP at 280 W. I have included the AVX2 values here for the Intel processors, however at AVX512 these will turbo to 296 W (i9-11900K) and 291 W (W-3175X).

AMD TR Pro Review: 3995WX, 3975WX, 3955WX CPU Tests: Rendering
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  • DesireeTR - Wednesday, July 14, 2021 - link

    OK, found the news too. IDK if I can link any other website here other than Anandtech, but look for "Lenovo is Using AMD PSB to Vendor Lock AMD CPUs" from servethehome, dated April 5th 2021. Lenovo P620 with Threadripper Pro was tested and found that they used the strict PSB lock-in like Dell do on their PowerEdge servers.
  • Threska - Wednesday, July 14, 2021 - link

    I think "permanently" is the biggest concern, otherwise it could be a great feature as part of a "root of trust" if the user could control it, especially via hardware modification. e.g. jumper.
  • DesireeTR - Wednesday, July 14, 2021 - link

    Yeah, and if this trend continues, the Ryzen PRO definitely is next on the line getting this PSB. Laptops might be OK, since they use soldered BGA processor anyway, but definitely a big no no for prebuild towers.
  • arashi - Saturday, July 17, 2021 - link

    If it can be overridden like that then it isn't a root of trust anymore.
  • Threska - Saturday, July 17, 2021 - link

    There's the presumption you trust yourself.
  • Mikewind Dale - Wednesday, July 14, 2021 - link

    Dear Anandtech: If you ever review the motherboards, I'll relate something a few things I discovered about the Supermicro M12SWA-TF:

    First, it cannot use sleep mode. If you put the computer to sleep, then when you wake it up, the fans will all spin at low RPM, and they will fail to adjust to temperature. HWiNFO64 reports two sets of sensors: one set is direct, and the other is indirect, via the IPMI. After waking from sleep, the direct sensor readings were still reported, but the indirect-via-IPMI sensors were all null. When I logged into the BMC/IPMI, all the sensors were null there too. And when I ran a CPU burn-in after waking from sleep, my CPU temperature quickly climbed higher than normal, and the fans did NOT ramp up their RPM. (I was prepared for this, so I was running only a single-threaded CPU benchmark.)

    Not only did rebooting the computer fix the problem, but so did Windows hibernate. The fact that Windows hibernate fixed the problem told me that the problem was hardware, not OS.

    I contacted Supermicro, and they said this behavior is normal (!!!!!!). They explained that the IPMI controls the fan RPM, but it only connects to the sensors during POST. If you put the computer to sleep, the IPMI loses its connection to the sensors, and it cannot resume that connection until the computer POSTs again.

    So if you review the motherboards, make sure to test the sleep behavior.

    Second, the Supermicro board is programmed with critical low fan RPM threshholds that are lower than Noctua's RPM. If you Google, you'll see a lot of people have problems with using Noctua fans with Supermicro boards. What happens is, the the Noctua fan's RPM will drop below the critical low RPM threshholds, so the Supermicro board will think the fan is failing, and it will quickly ramp the fan up to 100% PWM. Once the fan exceeds the critical low RPM threshold, the alert will end, and the fan will drop its RPM back down again, starting the cycle over. So the fans cycle back and forth between high and low RPM. When I logged into the IPMI, I saw that I every single fan was triggering the low RPM alert every few seconds.

    The solution is to reprogram the IPMI with new critical low RPM thresholds. Supermicro's own IPMI software does NOT allow this, because Supermicro explained to me that some people have overheated and fried their motherboards using insufficient cooling. So I had to use a third-party tool called "ipmitool".

    Usually, ipmitool is obtained via "sudo apt-get install ipmitool". However, I found that the Linux version was unable to establish a connection with my BMC, even though other IPMI tools had no problem with establishing that connection. But other IPMI tools did not have the ability to reprogram the fan thresholds.

    Luckily, the Windows version of ipmitool was able to establish a connection and alter my fan thresholds just fine. The Windows version is available at https://www.dannynieuwenhuis.nl/download-windows-i...

    If you Google, you'll find many, many different websites offering instructions for how to use ipmitool to modify your Supermicro board to be compatible with Noctua fans. I'll just give a few sample lines of code here, in case anyone needs them:

    ipmitool -I lanplus -H <ipaddress> -U <username> -P <password> sensor thresh FAN1 lower 40 140 240
    ipmitool -I lanplus -H <ipaddress> -U <username> -P <password> sensor thresh FAN1 upper 1650 1750 1850

    --- FAN1 is the name of the fan header, as labeled in the motherboard manual. Options are FAN1-FAN6 and FANA-FAND.
    --- "lower" numbers are lower non-recoverable, lower critical, and lower non-critical, in that order.
    --- "upper" numbers are upper non-critical, upper critical, and upper non-recoverable, in that order.

    To calculate the thresholds, I did the following:
    First, I looked up Noctua's specs. FAN1 is my Noctua NH-U14S TR4-SP3. According to Noctua, its fan's RPM are 300 +/-20% to 1500 +/- 10% RPM.
    Second, I set the lower non-critical to 300*0.8 (i.e. -20%) and the upper non-critical to 1500*1.1 (i.e. +10%).
    Third, for the critical and non-recoverable thresholds, I just added or subtracted 100%.

    Do the same for every other fan in every other header. I wrote about every line in a .BAT file in Windows, which read like this:

    REM **************************************************************************************************
    REM **********
    REM FAN1 is Noctua NH-U14S TR4-SP3: 300 +/-20% to 1500 +/- 10% RPM
    REM **********

    ipmitool -I lanplus -H <ipaddress> -U <username> -P <password> sensor thresh FAN1 lower 40 140 240
    ipmitool -I lanplus -H <ipaddress> -U <username> -P <password> sensor thresh FAN1 upper 1650 1750 1850
    REM **************************************************************************************************

    REM **************************************************************************************************
    REM **********
    REM FAN2 is Noctua NF-A15: 300 +/- 20% to 1200 +/- 10%
    REM **********

    ipmitool -I lanplus -H <ipaddress> -U <username> -P <password> sensor thresh FAN2 lower 40 140 240
    ipmitool -I lanplus -H <ipaddress> -U <username> -P <password> sensor thresh FAN2 upper 1320 1420 1520
    REM **************************************************************************************************

    and so forth, for every fan header. This successfully solved the problem of the fans triggering the threshold alerts and cycling up and down.
  • Mikewind Dale - Wednesday, July 14, 2021 - link

    "Second, the Supermicro board is programmed with critical low fan RPM threshholds that are lower than Noctua's RPM."

    I meant *higher*. The Supermicro default critical low fan RPM thresholds are *higher* than Noctua's.
  • Mikewind Dale - Wednesday, July 14, 2021 - link

    Oh, and because sleep mode is dangerous, threatening to potentially fry your CPU (since the fans no longer respond to temperature), I not only set my computer never to sleep, but I removed sleep from the power options in the start menu. That way, I cannot accidentally put the computer to sleep.

    If you do ever put your Supermicro M12SWA-TF to sleep, you will not receive any alerts that every sensor is null. If you log into the BMC, you'll see every sensor is null, but there are no alerts. And the fans all spin at minimum RPM regardless of your fan setting, and regardless of temperature. So sleep mode appears to have the potential to fry your CPU.
  • Threska - Wednesday, July 14, 2021 - link

    You keep saying "fry" but haven't CPUs had thermal protection for ages at this point?
  • Mikewind Dale - Wednesday, July 14, 2021 - link

    Threska, possibly. But I didn't want to find out.

    At best, sleep mode would cause the computer to constantly downclock or shut down without any clear cause (unless the user realized it was because sleep mode deactivated the IPMI's reporting of the sensors while the sensors themselves were still reporting values to software such as HWiNFO).

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