Power Consumption and TDP

The way AMD and Intel use the term Thermal Design Power (TDP) is different. Technically it is a measure of cooling ability needed for a given processor, which is how AMD use it, or the more common way is a measure of power consumption, how Intel does it. The question becomes whether it means sustained power, or turbo power - most people assume it's the latter, but Intel use it for the former (sustained) power. We describe this in detail in our article here:

https://www.anandtech.com/show/13544/why-intel-processors-draw-more-power-than-expected-tdp-turbo

There is also the added factor of the luck of the draw - two processors that have the same name can potentially vary wildly in power consumption. Both AMD and Intel apply 'binning' rules, such that CPUs that hit a minimum grade are stamped as that processor model. This means that a processor can either only just pass the grade, or be a super perfect chip, but still be sold as the same. There is also the possibility that the company could downgrade a higher model and rebadge it to the lower model in order to adjust inventory. This is something to keep in mind when looking at power numbers.

Power Consumption

Power consumption was tested on the system while in a single MSI GTX 1080 GPU configuration with a wall meter connected to a power supply with ~75% efficiency > 50W, and 90%+ efficiency at 250W, suitable for both idle and multi-GPU loading. Our method of power reading actually bypasses the power management of the UEFI and the board to supply components with power under load, instead using the readings that the system is directly be told from the CPU for managing fan speeds, temperatures, current protection, etc. This way of reading the power has positives and negatives, but provides a sustainable CPU-only comparison value.

In our test, we use affinity masking to test from 0 to double the threads of the CPU while running the POV-Ray benchmark, and reporting the peak power from around ~20 seconds into the test when all threads are loaded. The 'Full Load' value takes the peak value out of all the affinity mark sub-tests. POV-Ray uses up to AVX2 instructions, which can draw more power than non-AVX code.

Power (Package), Full Load

As expected, the 2500X consumes more power than the 2300X, but both are beaten by almost 10W by the Core i3-8350K, and the Core i5-8600K sits in between the two AMD chips. Perhaps suprisingly, our Ryzen 5 2500X sample consumes more power at load than our Ryzen 5 2600 chip, which is rated at the same TDP. It would appear that the 65W TDP of our Ryzen 5 2500X is set too low, or we just have a bad chip that is applying a lot of voltage. The winners in power here are the Ryzen APUs.

Gaming: F1 2018 AMD Ryzen 5 2500X and Ryzen 3 2300X Conclusion
POST A COMMENT

62 Comments

View All Comments

  • romrunning - Monday, February 11, 2019 - link

    It may just be me, but all of the links on the "Pages In This Review" at the bottom of the main page simply return me to the main page. Reply
  • romrunning - Monday, February 11, 2019 - link

    But the drop-down to the specific page works as expected. Reply
  • evilspoons - Monday, February 11, 2019 - link

    It's definitely not just you. I spent a few tries wondering what I was doing wrong and re-read the start of the article until I tried the drop-down menu instead of the links. Reply
  • Ian Cutress - Monday, February 11, 2019 - link

    That's my fault, as the hyperlinks need to be manually added. I had messed up the part of the URL after the /show/13945. It should be fixed now. Reply
  • Kevin G - Monday, February 11, 2019 - link

    I noticed this as well. Reply
  • meltdowner - Monday, February 11, 2019 - link

    R5 2600 all day. These are nice processors for smaller machines, though. Reply
  • GigaCat - Monday, February 11, 2019 - link

    Heck, even a 2600 can sit comfortably in a HTPC with low-profile cooling. Reply
  • IGTrading - Monday, February 11, 2019 - link

    Thank you Ian for a good review.

    I completely agree with the conclusion that the 2300X makes perfect sense, but the 2500X is harder to place in the picture ...

    On the other hand, despite 2400G and the 2500X have the same TDP, if I look at the graph with full load power consumption, I can clearly see that the latter has a very generous thermal limit, compared with the 2400G where the thermal envelope seems to be very strictly limited.

    Meaning OEMs will probably be able to use the 2500X for cheaper gaming systems where auto-overclocking is used as a feature and AMD will thus be able to offer something better for a lower price.

    This also allows AMD to push AM4 harder on the market, giving itself the opportunity to future upgrades for AM4 buyers.

    So the 2500X will show considerably better performance than the 2400G despite the similar config (minus the iGPU) while not cannibalizing the 2600 nor the 2400G.

    If AMD manages to sell more 2500X through OEMs, AMD also builds a future upgrade market for itself, unlike Intel that will likely push buyers into purchasing new machines.
    Reply
  • dromoxen - Monday, February 11, 2019 - link

    ppl buying these CPUs are not the sort to be upgrading the CPU.. to most the computer is a closed box and is upgraded as a whole . I do wonder where all these cores are going .. I mean its great to have 4 6 8 cores with another 8 hyperthreads .. but who is using all that power ? Lets make 4 cores the absolute limit , unless you have a Govt permit to purchase more. Reply
  • GreenReaper - Monday, February 11, 2019 - link

    Browsers have been getting a lot better at using multiple cores, and websites surely do enough in the background nowadays to justify the effort. Reply

Log in

Don't have an account? Sign up now