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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  • Qasar - Tuesday, July 27, 2021 - link

    sorry but that is not HEDT, workstation, sure. the last HEDT platform intel had was x299 and socket 2066
    socket 3647, is there server/workstation platform, but hey if you consider a US $3k cpu to be a HEDT processor, then that's your choice :-)
  • mode_13h - Monday, July 26, 2021 - link

    > at least amd HAS a HEDT cpu, when was the last one from intel ?

    Intel is doing an Ice Lake workstation platform. Not sure if HEDT will follow.
  • mode_13h - Sunday, July 25, 2021 - link

    > 7 days to August

    The rumor was that it would be *announced* at some point in August. It didn't say when, in August, but the rumored ship date wasn't until sometime in September. But it's just a rumor.
  • croc - Monday, July 26, 2021 - link

    MY point is that the BIOS updates usually happen about a month before the product announcement. Not to mention some benchmarks and other 'leaked' information. Y'know,,, Hype generation, direct from horsey's mouth. August announcement? Don't think so. Chagall? Possible, but would break convention, not that AMD really has any when it comes to code names...
  • mode_13h - Monday, July 26, 2021 - link

    > BIOS updates usually happen about a month before the product announcement.

    Before announcement or ship?

    > Hype generation

    Seems to me that it's not necessary, in this case. AMD will already have more demand than it can satisfy.
  • Qasar - Tuesday, July 27, 2021 - link

    " Not to mention some benchmarks and other 'leaked' information "
    considering how few leaks and info have come out about amd's products as of late until quite close to release, im not surprised there is little info out there about zen 3 TR

    " Hype generation "
    which amd doesnt need all that much, their products are more interesting then intels right now, intel needs the hype, not amd ;-)
  • Mikewind Dale - Monday, July 19, 2021 - link

    Given how much trouble Intel has had with their new process - even though Intel used to be the industry leader in fabrication - I suspect that if AMD had kept fabrication in-house, they'd be in serious trouble right.

    GlobalFoundries has also had trouble moving to a new, cutting-edge process. At the moment, they'd decided to stay one process behind TSMC, and cater to the portion of the market that doesn't need a cutting-edge process.
  • anakhizer - Monday, July 19, 2021 - link

    The article is excellent! However, the ordering of data in the tables is absolutely terrible.

    Please figure out how to sort the tables in a more logical manner like performance. As the tables are they are pretty much unreadable if you want to get the performance numbers with a glance.
  • kensiko - Monday, July 19, 2021 - link

    Performance wise, looking at all those graphs, the 5950x is such a great deal ! I really love my 5950x. I did love my TR1950x, it was not getting as hot at my 5950x. But no way I'm going back to Threadripper for just a home PC. Event at work I don't think we would get a Threadripper again, the Epyc gives what we want even if the frequency is a bit lower.
  • mode_13h - Tuesday, July 20, 2021 - link

    Threadripper still makes a lot of sense for people who have scalable workloads (or run lots of VMs) and who don't need the full memory bandwidth or PCIe lanes of EPYC or TR Pro.

    I personally wouldn't buy one, but they're popular for deep learning workstations and Linus Torvalds famously has one.

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