Power Consumption

For our power consumption metrics, we use a Prime 95 blend on fixed threads to generate a strong load, and then poll the internal power registers that determine power state calculations to get the power consumption. Each processor is different in how it reports its power, which depends on the level of control the processor has: some of the more advanced CPUs, such as Ryzen, will provide per-core power numbers, while the latest Intel CPUs only give a figure for the CPUs as a whole but also include DRAM controller and uncore power consumption.

An interesting element to the power consumption on the Ryzen APUs, due to the unified power delivery subsystem in play feeding the CPU and the integrated graphics, is that the power registers only report half the power consumption when probed (e.g. when 14W, shows 7W). As of yet, we are unsure if this has a knock-on effect on how the processor adjusts its turbo modes in response to power consumption. Nonetheless, a simple scaling factor gives the following results.

Total Package: The Whole Processor

For this data, we take the values of the processor as a whole, which includes all the interconnect, memory controllers, PCIe root complexes, etc. The system is still only loading the CPU cores with minimal effect on the rest of the system, however depending on how the power is managed, some of the sub-systems still remain enabled.

Power: Total Package (1T)Power: Total Package (Full Load)

At full load, the difference between the Ryzen 5 and the other Ryzen CPUs shows that the 2400G is using more of its upper margin, compared to the 1400 which is rated at the same power (note TDP is only determined at the base frequency), but the extra frequency of the 2400G means that there is extra power draw overall. Part of this is due to the Infinity Fabric, which we will see below. But what these tests also underline is that in a quad-core configuration, the Intel CPUs are still very power efficient.

Cores Only: Pure Work

For the processors that split out the data, we can look at the power consumption of the cores on their own, without any of the sub-systems, like uncore, mesh, or infinity fabric. This usually paints a different picture to the package power.

Power: Cores Only (1T Load)Power: Cores Only (Full Load)

For the core only power, the Ryzen 5 2400G uses less power than the Core i3-8350K, despite the situation being reversed when considering the whole package. This means that Infinity Fabric takes a lot of power here, and the ring bus solution that Intel uses benefits from being simpler, and Intel can push more power to its individual cores.

Benchmarking Performance: CPU Legacy Tests Conclusion: Cutting Low-End Discrete Graphics
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  • coolhardware - Monday, February 12, 2018 - link

    I have been holding on to my Intel 2500K desktop for what seems like forever. It has been a trusty companion but with a TDP of 95W and a dedicated GPU pulling 100W+ I'm looking for something a little less power hungry. AMD seems to have what I've been looking for and the price is right :-)

    Amazon has the 2400G in stock, http://amzn.to/2BVzSSn and I think I'm going to bite the bullet!

    PS does anybody have a mobo recommendation for pairing with the 2400G? (stability is my main concern, probably won't OC since the 2400G should be a nice step up from my 2500K)
    Reply
  • zaza - Monday, February 12, 2018 - link

    if already have a decent GPU it is better to get the Ryzen 1600 instead. it is only 10 or 20$ more but you will get two extra and 8 extra PCIe lanes. These APU only make sense as a placeholder to get something better, for example building a working PC, then add a dedicated GPU later. Reply
  • haukionkannel - Monday, February 12, 2018 - link

    Or this will get you very good office computer, without ever needing external GPU... Reply
  • forgerone - Tuesday, February 13, 2018 - link

    EXACTLY!!! This is the market for Ryzen with Vega. Business PC's and Laptops and also economy gaming for the markets that can not afford discrete GPU AIB. Reply
  • coolhardware - Monday, February 12, 2018 - link

    Cool, thanks for the tip! How is discrete non-gaming (desktop, Photoshop) GPU power usage these days? I live off the grid and so energy efficiency is a big plus. I do not game much so (SC2 and some lower end Steam games).

    Also, any suggestions for motherboards for 1600 or 2400G? Again, stability is top criteria for me.

    Last question, what's the max number of video outputs for the 2400G? Thx!
    Reply
  • coolhardware - Monday, February 12, 2018 - link

    PS I currently have a GTX 960. It does look like a step down versus the 2400G, as ~1030 (similar benchs to 2400G) is quite a bit lower speed than a 960:
    http://gpu.userbenchmark.com/Compare/Nvidia-GTX-96...
    Reply
  • Cellar Door - Monday, February 12, 2018 - link

    The 960 is 2-3x the performance of this. Reply
  • Samus - Monday, February 12, 2018 - link

    GTX960 is a $200+ GPU. It's substantially faster than any integrated graphics and probably will be for the next few years. Reply
  • msroadkill612 - Tuesday, February 13, 2018 - link

    " I live off the grid and so energy efficiency is a big plus." - apuS are exactly what you should be using. Reply
  • WorldWithoutMadness - Monday, February 12, 2018 - link

    then might as well wait for ryzen+ version.

    Seriously AMD need to release something akin to NUC using the Raven Ridge. They can rake quite a lot of market with that. I will change my office's PCs with those, better GPU and comparable CPU.
    Reply

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