Thursday, April 13, 2017

Some Ryzen power draw data

Ok so I finally have a operational Ryzen system and while the BCLK controls in the BIOS are being stupid I can still do other testing so here is that other testing.

The goal of this data is to figure out how the power draw of Ryzen is split between the cores and everything else like the SOC. For my testing I'm using Asrock's X370 Taichi and a Ryzen 7 1700. I'm not 100% sure how the 12V of the single 8pin CPU power connector is distributed but for the most part it doesn't matter because the focus here is figuring out core power draw in order to be able to gauge Vcore VRM requirements for overclocking.

So here is the data! Do note it is rather rough as far as error margin goes because CPU temperature was not maintained across test runs and higher temperatures do lead to elevated power draw. I didn't bother with more accurate measurement methods because chip to chip variance will cause larger power draw discrepancies than my measurement methods for this data.

Clock Voltage Core Config Power Draw
3.95Ghz 1.45V 4+4 170W
3.95Ghz 1.45V 3+3 135W
3.95Ghz 1.45V 2+2 100W
3.95Ghz 1.45V 1+1 60W
3.95Ghz 1.45V 4+0 100W
3.95Ghz 1.45V 3+0 75W
3.95Ghz 1.45V 2+0 65W
All tests were done with SMT turned on.

From this we can see that 1 core with SMT at 3.95GHz 1.45V consumes roughly 17W. The other things hooked to the 8pin connector pull a constant 30W. I suspect that most of this 30W would be the SOC portion of a Ryzen CPU.

This means that for an 8 core Ryzen chip Vcore current draw at 4Ghz/1.45V is only about 96A. 6 core CPUs would be about 72A and 4 cores only about 48A. Basically that means the Vcore VRM current through put required for your motherboard to not go up in flames is absolutely minuscule. Basically any AM4 motherboard should be capable of doing 4Ghz or more on 6 core CPUs. Motherboards with good 4 phase VRM designs should also have no issue pushing 4Ghz on 8 core CPUs.

Now of course this is only looking at current capability. Better VRMs also have better voltage regulation as well as current through put which means that they may clock a little better for any given voltage just because it won't fluctuate as much as it does on weaker VRMs. However it does mean that for daily OCs you really don't need the insane VRMs that come on boards like the Gigabyte Gaming K7, Asrock X370 Taichi/Professional Gaming or Asus Crosshair 6 Hero.

Also thanks to all the Patreons and shirt buyers for making this article possible!


  1. Super useful for VRM calculations ;)

  2. What voltage was your SOC when it was likely taking 30W?

    1. This comment has been removed by the author.

  3. thinking of buying
    ryzen 5 1400 @ 3.7 on gigabyte gaming 3 AB350M concerned about vrm temps

  4. I have a question regarding power in the Ryzen I was hoping you could help me with. Long story short, I've been upgrading my office piece by piece for my PUBG addiction. Each upgrade makes me uneasy because of the motherboard I'm using. Asrock (A320-M rev. 4.0) I flashed her and threw in a 3600 and a 1660 card...and a Corsair RM-750 for juice. Surprisingly, I am extremely pleased with my performance, rock solid framerate. (2400g previously installed could never stabilize frames in that game) to the issue...

    At the most CPU intensive parts of the game I occasionally bump up to critical thermal limit for the core, I'm assuming it throttles down for a brief bit because temps drop off a cliff suddenly and my RivaTuner scanline sync gets all outta whack. (im assuming its related) I read a lot of articles about how the 3rd gen Ryzens are usually pretty good in the thermal department so, I assume that I'm running hot because of the basic-ass VRM I have throwing juice at the CPU. Anyway, I ordered a tower cooler for the CPU and plan on installing I making a common mistake thinking that just removing the heat is that thermal throttle effectively the ONE thing stopping crappy voltage management from doing damage to itself or the CPU??? Any thoughts/advic...or criticism lol would be much appreciated. Thanks.

    PS: Not overclocking