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 hardcoded, 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 that 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 of 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 workflows, real-world image-model construction, 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 image-model construction workload, using our Agisoft Photoscan benchmark. This test has a number of different areas that involve single thread, multi-thread, or memory limited algorithms.

For the Ryzen 7 5700G, the most power-hungry part of the test is right at the beginning, where we’re seeing peaks of 85 W. For the 5600G, that first section goes to 65 W, but the peaks actually occur here near the end of the test. The 5300G also has peaks later in the test, but that first section is the lowest, running only at 46 W.

The second test is a sustained rendering workload.

In this instance, the Ryzen 3 5300G is nearer 55 W with a sustained workload over 10 minutes, while the Ryzen 5 and Ryzen 7 sit just below 80 W.

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

(0-0) Peak Power

While all three processors have a TDP rating of 65 W, by default on AMD systems the Package Power Tracking, which is the limiting factor here, is 88 W. The Ryzen 7 is practically at that value, while the Ryzen 5 just goes a smidge over 80 W. The Ryzen 3 on the other hand only matches its TDP in the worst-case scenario.

The AMD Ryzen 5000G APUs: Cezanne Silicon Microbenchmarks
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  • Wereweeb - Wednesday, August 4, 2021 - link

    The bottleneck is memory bandwidth. DDR5 will raise the iGPU performance roof by a substantial amount, but I hope for something like quad-channel OMI-esque Serial RAM.
  • abufrejoval - Saturday, August 7, 2021 - link

    I'd say so, too, but...

    I have just had a look at a Kaveri A10-7850K with DDR3-2400 (100 Watt desktop), a 5800U based notebook with LPDDR4 (1333MHz clock) and a Tiger Lake NUC with an i7-1165G7 with DDR4-3200.

    The memory bandwidth differences between the Kaveri and the 5800U is absolutely minor, 38.4 GB/s for the Kaveri vs. 42.7GB/s for Cezanne (can't get the TigerLake figures right now, because it's running a Linux server, but it will be very similar).

    The Kaveri and Cezanne iGPUs are both 512 shaders and apart from architectural improvements very much differ in clocks 720MHz vs. 2000MHz. The graphics performance difference on things like 3DMark scale pretty exactly with that clock difference.

    Yet when Kaveri was launched, Anandtech noted that the 512 shader A10 variant had trouble to do better then the 384 shader APUs, because only with the very fastest RAM it could make these extra shaders pump out extra FPS.

    When I compared the Cezanne iGPU against the TigerLake X2, both systems at tightly fixed 15 and 28Watts max power settings, TigerLake was around 50% faster on all synthetic GPU benchmarks.

    The only explanation I have for these fantastic performance increases is much larger caches being very smartly used by breaking down GPU workloads to just fit within them, while prefetching the next tile of bitmaps into the cache in the background and likewise pushing processed tiles to the framebuffer RAM asynchronously to avoid stalling GPU pipelines.

    And yet I'd agree that there really isn't much wiggling room left, you need exponential bandwidth to cover square resolution increases.
  • abufrejoval - Saturday, August 7, 2021 - link

    need edit!

    Is TigerLake Xe, not X2.

    Another data point:

    I also have an NUC8 with an 48EU (+128MB eDRAM) Iris 655 i7 and a NUC10 with an 24EU "no Iris" UHD i7. Even with twice the EUs and the extra eDRAM (which I believe can be used in parallel to the external DRAM), the Iris only gets a 50% performance increase.

    The the 96EU TigerLake iGPU is doing so much better (better than linear scale over UHD) while it actually has somewhat less bandwidth (and higher latency) than the 50GB/s eDRAM provides for the 48EU Iris.
  • bwj - Wednesday, August 4, 2021 - link

    Why are these parts getting stomped by Intel and their non-graphics Ryzen siblings?
  • bwj - Wednesday, August 4, 2021 - link

    Meh, meant to say "in browser benchmarks". Browser is an important workload (for me at least) and the x86 crowd is already fairly weak versus Apple M1, so I'm not ready to throw away another 30% of browser perf.
  • Lezmaka - Wednesday, August 4, 2021 - link

    There are only 3 browser tests and for two of them the 5700G is within a few percent of the 11700K. But otherwise, it's because these are laptop chips with higher TDP. The 11700K has a TDP of "125W" but hit 277W where the 5700G has a TDP of 65W and maxed out at 88W.
  • Makaveli - Wednesday, August 4, 2021 - link

    There is something up with the browser scores here anyways compared to what you see in the forum. All the post with similar desktop cpu's in that thread post much high scores than what is listed in the graph. I'm not sure its old browser version being used to keep scores inline with older reviews or something.

  • abufrejoval - Wednesday, August 4, 2021 - link

    When you ask: "Why don't they release the four core variant?" you really should be able to answer that yourself!

    There are simply not enough defective chips to make it viable just yet. Eventually they may accumulate, but as long as they are trying to produce an 8 core chip, 4 and 6 cores should remain the exception not the rule.

    I'd really like to see them struggle putting the lesser chips out there, because it means my 8/16(/32/64) core chips are rock solid!

    I would have liked to see full transistor counts of the 5800X and the 5700U side by side. My guess would be that the Cezanne dies even at 50% cache have more transistors overall, meaning you are getting many more pricey 7nm transistors per € on these APUs and should really pay a markup not a discount.

    Well even the GF IO die fab capacity might have customers lined up these days, but in normal times those transistors should be much more commodity and cheaper and have the APU cost more in pure foundry (less in packaging) than the X-variants, while AMD wants to fit it into a below premium price slot where it really doesn't belong.
  • nandnandnand - Wednesday, August 4, 2021 - link

    If AMD boosted chiplet/monolithic core count to 12, maybe 6 cores could become the new minimum with 10-core being a possibility. But it doesn't look like they plan to do that.
  • Wereweeb - Wednesday, August 4, 2021 - link

    These might have been a stockpile of dies that were rejected for laptop use (High power consumption @ idle?) and they're being dumped into the market after AMD satisfied OEM demand for APU's.

    Plus, considering that one of the main shortages is for substrates, it's possible that the substrate for the APU's is different - cheaper, higher volume, etc... as it doesn't need to interconnect discrete chiplets.

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