Windows 10 is causing issues with CPU affinity and is limited to just three cores.
Windows 10 is causing issues with CPU affinity and is limited to just three cores.
Hello everyone, this is my first time here! I’m facing some issues with my Windows installation lately. It seems the system automatically assigns CPU cores to almost every program, putting most of them on cores 0, 1, and 2, while leaving the rest underused—usually around 15%. This means in normal use, the first three cores are fully utilized, and the remaining ones barely get any work. I’ve also noticed this problem with critical Windows apps like svchost. I searched online for a solution but only found instructions on how to specify cores via command line when launching an app. It feels like there should be a more convenient way. I’m wondering if someone could help me resolve this.
My setup details: AMD Ryzen 5 5600X, NVIDIA GeForce RTX 3060 Ti, Corsair Vengeance RGB Pro 4x8 at 3200Mhz, paired with an ASUS Rog Strix B550-F. I have several SSDs, HDDs, and one M.2 SSD. If you need more info, just let me know—I’ll do my best to assist.
Are those cores operating at full capacity while it continues running? If not, it could simply be conserving power by allowing other cores to rest. I recall that during lighter usage, my 5950X tends to run on about three cores, but it activates all of them when the load increases.
If I observe it correctly, this suggests adjusting the affinity settings. In Windows, I already manage this, but the issue is that each time I restart the system, those changes are lost. For example, when I start my PC in the morning, most applications are configured to run on just three cores. I manually override them to use all available cores, which takes a long time since I have to do this for nearly every process. After turning off the computer and leaving it on, the next day all these changes are undone, forcing me to reset the affinity each day repeatedly. I don’t think this is the main problem because even when all cores are enabled, they still default to using only three. Here’s a screenshot to illustrate my point: the fact that my Windows interface is in Italian makes it clear what I mean—I simply selected a random program (Discord) and Windows instructed it to run on just the first three cores.
After installing the chipset drivers, I conducted some testing and must admit I was quite surprised by the outcome. While checking, I discovered that CPU affinity shifts when launching games or demanding applications like UE4. The main issue turned out to be Razer Cortex, which began working together with it. (Razer software includes a utility that optimizes PC performance during game launches, and so far it performed well by clearing excess RAM.) Upon further investigation of the optimization settings in Razer Cortex, I found a problematic configuration. It forces the running game or program to utilize all cores, while limiting everything else to just three. This forces those three underperforming cores to work harder while others lag—like when sharing screenshots on Discord. This behavior likely stems from a recent update in Razer Cortex, possibly due to changes in the UI and optimization logic. Turning off this setting resolved the problem, and since the system ran smoothly afterward, I’m confident it was the root cause. Thank you all for your assistance; finding a solution was a relief.