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3 tweaks that helped me reduce CPU bottlenecks while gaming
Ever since I upgraded to the RTX 4090, I've noticed how often my games feel held back by my CPU. My old Ryzen 9 5900X just couldn't keep up with the kind of frame rates the GPU was capable of pushing, especially in fast-paced competitive shooters and even some open-world games. Most of the time, my GPU usage would sit at around 80%, which is a clear sign that my CPU is the bottleneck. It's the main reason why I upgraded to the 5800X3D earlier this year when my CPU died out of nowhere.
Although my GPU usage has significantly improved, I still experience bottlenecks in some CPU-bound games, especially at lower resolutions. I'm well aware that the 5800X3D is not the best option for my 4090, and I could've bought a newer CPU, but that'd mean spending more on a new AM5 motherboard and DDR5 RAM kit. That's why I rely on tweaks to help reduce CPU bottlenecks as much as possible. With the right adjustments, I can squeeze more performance out of the hardware I already own.
Lowering CPU-bound graphics settings
It frees up CPU headroom and helps prevent dips during demanding scenes
Many gamers think graphics settings affect only the GPU, but that's not true for options like draw distance, population density, foliage density, and physics quality. Raising these settings puts more strain on the CPU by forcing it to track more objects, calculate more AI behavior, and process more world data every single frame. When your CPU already struggles to keep up with a powerful GPU, those extra calculations can push it over the edge, which is why lowering them can make a noticeable difference.
Sure, it may not always raise your average FPS all that much, but it can improve your 1% and 0.1% lows by a meaningful amount, and that alone can have a big impact on how games actually feel. Additionally, disabling DLSS can also help reduce CPU bottlenecks because lowering the internal resolution shifts load off the GPU and makes the game more CPU-bound. In fact, if your graphics card has plenty of headroom to run a game at native resolution, increasing GPU-bound graphics settings can take pressure off the CPU.
Undervolting for better boost clocks
Lowering CPU temps by undervolting helps it sustain higher clocks for longer
I'm sure many of you already know that modern CPUs run hot out of the box. It's why undervolting is more popular than overclocking these days. Most CPUs boost as high as they can until they hit a thermal or power limit, after which they start dropping their clock speeds to stay within the safe operating range. So, even a small reduction in voltage can lower temperatures enough to keep the CPU from throttling during long gaming sessions. And that extra thermal headroom is what allows the CPU to maintain higher boost clocks for longer.
For instance, my 5800X3D advertises a maximum boost clock of 4.5GHz. At stock voltage settings, it usually hovers around 4.3 GHz since the temperature is in the mid-80s, but after a minor undervolt, it maintains 4.4-4.5GHz as much as it can while running a couple of degrees cooler. That extra 100-200MHz may not seem like much, but I get more consistent frame rates and slightly better 1% and 0.1% lows. All in all, it's one of the easiest tweaks you can try to squeeze more performance out of your CPU with little to no downsides.
Enabling Resizable BAR
It lets your CPU access your GPU's VRAM more efficiently
In recent years, Resizable BAR has become a popular tweak among gamers looking for a small FPS boost, but most people don't realize where the gains actually come from. The feature basically removes the traditional 256MB VRAM access limit so that the CPU can pull much larger chunks of data from the GPU's memory at once. This allows the CPU to stream textures, geometry, and other assets more efficiently, reducing the small stalls that happen during busy scenes in open-world titles.
Resizable BAR won't dramatically improve your average FPS in most games, but it can help smooth out performance if you've paired a high-end GPU like the RTX 4090 or 5090 with an aging CPU like I have. You can enable it from the BIOS, whether you have an Intel or AMD CPU, and your GPU will do the rest through its drivers. For games that don't officially support it, you can force it manually using Nvidia Profile Inspector, although your results may vary depending on how well the game engine handles large VRAM mappings. Even if the gains are modest, it's a good idea to give your CPU that extra breathing room with ReBAR.
Get more out of your aging CPU with the right tweaks
You don't always need to rush to upgrade your CPU every time you encounter bottlenecks. At lower resolutions like 1080p and 1440p, especially with high-end GPUs, CPU bottlenecks are almost inevitable, even if you have a top-tier gaming chip like the Ryzen 9 9800X3D. Although you can't completely eliminate such bottlenecks, you can reduce how often they show up by tweaking settings that give your CPU a little more breathing room during demanding moments. Sometimes, improving the 1% lows is all it takes to get a smoother gaming experience, not big jumps in average FPS.
