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How to fix disabled AMD Ryzen processor cores

AMD Ryzen 7
AMD Ryzen 7 (Image credit: Windows Central)

PCs are funny old beasts, and in the process of setting up my new Ryzen 7 2700X (opens in new tab) build I encountered a few ... hiccups. One of the more troublesome ones was the PC reporting that four of the eight cores were disabled, which I verified in several places and ran some benchmarks just to be sure.

I searched the web, trying anything and everything, including resetting the CMOS (aka the small onboard memory) on the motherboard by removing the battery and reflashing the BIOS. Nothing worked. But eventually I found a very simple thing did. All you need is AMD Ryzen Master.

Ryzen Master

If you have cores disabled, Ryzen Master or Windows 10 Task Manager will show you.

I'll preface this by saying that this is by no means a guaranteed fix for your system. In my case, one very specific set of events triggers the cores to be disabled and this method has, so far, always brought them back.

Update: As folks have been asking in the comments, the set of events that triggered it in this example was applying XMP profiles and manual speed increases to the system's RAM in the BIOS. The issue is (in my case anyway) in no way linked to Windows 10 or the Ryzen Master application, which wasn't used for anything but the steps below.

If you don't have AMD Ryzen Master installed on your PC, you can grab it here.

How to enable disabled AMD Ryzen cores

Just follow these steps:

  1. Open Ryzen Master.
  2. Locate and click the reset button in the top right corner.

  1. Click OK when the dialog box pops up.

  1. Allow the PC to reboot and open up Ryzen Master again.

Assuming all went as planned, you should now see no disabled cores, as in the image above. Ryzen Master allows you to disable cores manually, and everything you do is at your own risk. But, thankfully, the big old reset button seems to do its job.

Ryzen Master is a piece of software that many will not use, and there's definitely a strong case to avoid it for purposes of overclocking, where you'll almost always be better off sticking to the BIOS. But, it definitely has a use, even if it's just to quickly set things straight if you're having a problem.

Richard Devine is an Editor at Windows Central. A former Project Manager and long-term tech addict, he joined Mobile Nations in 2011 and has been found on Android Central and iMore as well as Windows Central. Currently you'll find him covering all manner of PC hardware and gaming, and you can follow him on Twitter and Instagram.

9 Comments
  • This is confusing.
    Is this a hardware issue or a Windows issue? Were those cores disabled in BIOS or Linux too? If yes, how do you fix this in Linux? If you can't, well the hardware is defective.
  • Yep, you say this is not a sure fix Richard, and that a specific set of events can trigger the failure, but you don't mention what events cause this possible hardware failure? Has AMD commented yet? Is a more universal fix on the way? Do the original Ryzen chips suffer from this flaw as well, or just the new versions? Or is this just Microsoft acting up again as per usual? Please, a little detail would be useful here.
  • It is nothing to do with Windows. I don't even know how Windows could disable half the cores on a CPU. I triggered it by messing around with overclocking my RAM, trying to get it running at the speed on the box. Other people have seen the issue for different reasons. It has nothing to do with Microsoft and I've added an update. It has everything to do with me poking around in the BIOS and breaking things. I don't know why the cores go off, but they do, and this brings them back. Other people have had the same issue for presumably different reasons, worked for them too. It's worth trying, hence writing this post. Sure as hell better than RMA when you don't need to.
  • Seems more like Ryzen Master corrupt/incorrect settings to me.
  • Ryzen Master isn't responsible. The cores are disabled from messing around in the BIOS. But what Ryzen Master did do was fix it when no amount of BIOS tinkering could.
  • I don't use Linux. I don't write for Linuxcentral dot com.
  • You said that "one very specific set of events triggers the cores to be disabled". Can you elaborate?
  • Sure. Me messing around with overclocking my memory.
  • In Ryzen Master, disable "Legacy Compatibility Mode" and you have all 8 cores. It is off by default unless the user turns it on with "Game Mode" presets. You can also turn it off by using "Creator Mode" presets which is the same as the default settings.