Is your powerful computer acting slow?
Is your powerful computer acting slow?
I've had the same problem playing Apex Legends, which is actually my main game. It seems Assassin's Creed, Helldivers, and Hogwarts Legacy work fine for me because I just play them casually on a controller while sitting in bed, not focused right at the screen. But Apex keeps getting stuttery when I run it. The best thing I can do is open Task Manager next to Siege so that only the game uses up my CPU and memory; everything else stays low on usage (3% or less). However, Siege itself is using a lot of resources, so it's taking away from the other stuff running in the background.
Here is a video of how I'm testing it. You can see the stutters in the bottom left when the game hits a low frame count for a moment. To me, that feels like one CPU core is maxing out its power. I've tried different limits on frames per second, but even with 220 fps set to this cap, I get the same thing at 180, 100, or even around 400. It holds a steady number of frames for a bit before dropping by just a few and stuttering or freezing again.
Finally, looking at it on a big screen showed nothing about CPU speed. Individual cores hitting 100% isn't really a problem, but when all of them are maxed out, the system slows down. It might be worth checking system latency using LatencyMon to see if something specific is causing that slowdown. Are games and the OS on the same drive? Usually, that shouldn't matter much, but we're talking about very high frame rates here. Since you've tried capped frame rates lower this time, I'm not sure it's likely unless you have a full SSD. Fullscreen or Borderless mode generally speaking? I know you mentioned in the original post that something was using your video card causing worse issues, so maybe kill anything using the GPU and anything with overlays. Can't really think of anything else right now.
I have a separate drive just for games, while all my other games sit on a big 4tb drive. It's got over 2tb free space left there. My OS drive is full with lots of videos and a huge pagefile file (I don't know exactly why I created that). I've tried fullscreen and borderless mode but the problem stays the same no matter what. Even when I open only one tab or my usual ones like Spotify, Brave, and Discord, it still doesn't work. In the past, I ran these exact settings on my 2080 Super build with a Ryzen 3800X and it worked fine back then (though at much lower frame rates). Now I'm totally confused. It seems unlikely I'd have to close all other tabs just to get this game running. All I can see is that stuttering happens when the CPU hits 100%, making the CPU limit the GPU performance, but I really don't understand why that's happening right now.
This might be a very silly problem, but something could still be wrong with the riser cable. First, make sure your card is running PCIe 4.0 x16 using GPU-Z. I'm pretty sure it's doing that, but checking doesn't hurt. If it is, go into your BIOS and switch to PCIe 3.0 to see if anything changes. You've already had DDU done so far, so I don't think drivers are the issue right now.
I went into BIOS and changed the setting to 3.0 but when I started the game, GPU-Z still showed 4.0 for the graphics card. In any way, changing it didn't help with playing games. Have you watched that video? Did my CPU spikes on the cores match this change? If so, what can I do to lower the load on those CPUs? I've tried setting an FPS limit and just running with everything else turned off, but the game is still using all of its power because it's a Rainbow Six Siege run. Why doesn't that help me?
Do you think it is worth spending time on a full PC wipe and clean install? I feel like the game library has become so broken that I'm considering selling this machine to buy another computer or build something new from scratch. If none of those options work, maybe I'll try talking to my local pc specialist.