Whereas the graphics card is the most important component in any gaming PC, the CPU can also make a big difference. You might not even notice a CPU bottleneck in some cases, but a severe CPU bottleneck can ruin your gaming experience just as much as a major GPU bottleneck.

Explaining CPU Bottleneck

Before I dive into the deep end, let me explain CPU and GPU bottlenecks with the following analogy: Imagine that your CPU and GPU are two parts of a restaurant.

You’ve got the kitchen, filled with chefs, representing the CPU, and the dining hall filled with patrons, representing the GPU. Now, imagine that this particular restaurant offers just a few dishes, meaning you get your food the moment you order it.

The chefs (CPU) prepare the food (game data) and send it to the customers (GPU), who then consume it (render pixels on the screen).

Now, if the chefs are too slow, and you’ve got a bunch of ravenous patrons (a slow CPU coupled with a fast graphics card), they will devour the food (run the game at high frame rates), and then have to wait for the chefs to cook more.

This results in a high average frame rate accompanied by poor 1% and 0.1% lows that we perceive as stuttering. This happens because the GPU isn’t fed game data on time, resulting in periods where it sits idle.

The slower the CPU and the faster the GPU, the more frequent and severe instances of hitching will be. If the CPU is extremely slow, and you’re playing a CPU-demanding game, the hitching might be so severe you perceive it as freezing.

This is a CPU bottleneck. It can be bad news because most visual settings are GPU-bound so lowering the graphics options or dropping the resolution won’t improve things much.

On the other hand, if the chefs are good at their job and can cook the food so fast they create a surplus, you’ve got a GPU bottleneck. The slower the GPU, the lower the frame rate, but at least there won’t be any hitching. Also, if you’ve got a severe GPU bottleneck, you can lower the graphics settings, drop the resolution, or use upscaling to improve the frame rate.

In a perfect world, the CPU and GPU would be perfectly matched, and the chefs would cook food just in time for customers to consume it. But in reality, that’s hard to pull off. So, if you’ve got to choose, it’s better to have a GPU bottleneck than the other way around.

So, when is the CPU bottleneck severe enough to warrant a CPU upgrade?

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CPU Causing In-Game Stuttering? Upgrade It

In most games, a CPU bottleneck manifests as low GPU usage because the CPU cannot feed the GPU with data fast enough to saturate it.

To see whether your CPU is limiting your graphics card, you can use an in-game performance monitoring tool such as RTSS (Riva Tuner Statistics Server) in combination with MSI Afterburner, Intel PresentMon, or the built-in performance overlays available in NVIDIA and AMD GPU software.

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You want to enable CPU and GPU performance metrics and disable VSync and any in-game or external frame limiter so they don't limit in-game performance. Then, simply monitor your GPU and CPU utilization. If the GPU utilization is lower than about 95%, your CPU is most likely the bottleneck.

For example, if you check out the screenshot below taken in one of the busiest areas in Kingdom Come: Deliverance 2, you can see that my GPU utilization sits at 85%. In comparison, my CPU is 66% utilized (which is pretty high CPU utilization), which indicates a CPU bottleneck.

Similarly, the screenshot below shows Space Marine 2, a game that can push even the fastest gaming CPUs to their limits. As you can see, my GPU is only 86% utilized while the CPU sits at 80%, which is extremely high utilization for a CPU. This is another example of a CPU bottleneck.

If your performance metrics show similar data, you might consider upgrading your CPU, but only if you aren't satisfied with performance. If you aren't experiencing CPU-induced stutters and are satisfied with the frame rate you're getting, even if your GPU utilization is a bit lower than optimal, there's no need to get a faster CPU.

In-game stuttering doesn’t have to be caused by your CPU. It can be triggered by shader compiling, your PC not having enough RAM (having only 8GB of memory is going to be an issue in many modern games), or playing games with ultra textures and ray tracing effects with a GPU that packs 8GB of video memory or less. So, make sure the CPU is to blame before you consider replacing it.

CPU-Bound Games Run Poorly? An Upgrade Might Be in Order

Another instance where you might consider upgrading your CPU is if most games you play run fine, but CPU-bound titles don't meet your performance expectations.

Let's say you prefer playing esports titles and own a fast gaming monitor, say a 360Hz one. If you cannot achieve 360FPS in multiplayer games such as Counter-Strike 2 or Valorant, even with low settings while your GPU is underutilized (GPU usage is lower than 95%), your CPU is the performance limiting factor.

If your goal is to game at your monitor's max refresh rate, and you cannot achieve this with your current CPU, a faster CPU might do the trick. Just make sure to pick a CPU capable of delivering the level of performance you’re looking for.

Check out performance benchmarks and opt for a CPU capable of pushing enough frames to fully saturate your monitor's refresh rate.

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Similarly, some single-player games can be CPU-bound as well. After upgrading my GPU from an RTX 3070 to an RX 9070 XT, I was CPU bottlenecked in Kingdom Come: Deliverance 2. Luckily, I didn’t experience frequent stutters in that game, so I didn't really mind it.

On the other hand, I had constant CPU-induced stuttering in Cyberpunk 2077 with my old CPU, a Ryzen 5600X, which made the game near-unplayable. Cyberpunk 2077 with all settings cranked to the max and ray tracing enabled is a massive CPU hog.

While the performance was fine when standing still, moving or driving around the Night City would cause severe hitching. The only way of reducing stuttering was by lowering CPU-demanding options such as crowd density.

Upgrading to a Ryzen 5700X3D completely eliminated stuttering in Kingdom Come: Deliverance 2, as well as in Cyberpunk 2077 with crowd density set to "Medium" and ray tracing enabled. However, setting crowd density to "High" in CP 2077 was too big of a bite even for the 5700X3D.

I had a similar experience in S.T.A.L.K.E.R. 2 after upgrading my GPU, but before upgrading the CPU. The average FPS was fine, but I noticed occasional CPU-induced hitching when moving around the map.

Worse still, the game dropped to about 30 FPS with constant, heavy hitching when roaming around settlements, which made it virtually unplayable. Upgrading the CPU to a Ryzen 5700X3D solved most issues, but the frame rate didn't move past about 50 FPS in settlements coupled with poor GPU usage, as you can see on the screenshot below.

The reason why even the Ryzen 5700X3D struggles with S.T.A.L.K.E.R. 2 is because the game is one of the most CPU-heavy titles around. Entering any in-game settlement can bring even flagship gaming CPUs, like the Ryzen 9800X3D, to their knees. But hey, 50 FPS with an occasional stutter is miles better than 30 FPS with severe hitching.

If you notice that the performance in CPU-heavy single-player games is too poor for comfort while your GPU sits underutilized, upgrading your CPU will solve most, if not all, performance issues. Just make sure you get a CPU that packs enough power for the game you play and that the CPU is to blame in the first place.

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Not Every CPU Bottleneck Requires an Upgrade

Now, while you might have a CPU bottleneck, you shouldn't immediately start thinking about replacing your CPU.

If you're happy with the level of performance in games you play, even with a CPU bottleneck, there's no reason to buy a new CPU. Similarly, if you aren't bothered by occasional stuttering, you shouldn't upgrade your CPU.

I'm still CPU bottlenecked in certain games even with my new CPU, but I'm fine with that because I'm getting playable performance and don't want to spend a hefty amount of cash on a new motherboard, CPU, and RAM.

To alleviate a CPU bottleneck, you can lower CPU-related settings such as crowd density, LOD (level of detail, which can be both GPU and CPU intensive), vegetation quality and density, and physics-related settings to reduce the CPU load and see if that improves things. Disabling ray tracing effects could also help because ray tracing can put quite a load on the CPU in certain games.

Limiting your frame rate to a value your CPU can consistently deliver is another remedy for CPU bottleneck issues. For instance, if your CPU can consistently deliver 60 FPS without stuttering, but you notice hitching with uncapped frame rates, limit the frame rate to 60 FPS and enjoy stutter-free gameplay.

If you can achieve triple-digit frame rates some titles but cannot saturate your monitor's max refresh rate, try enabling frame generation if possible.

As long as you've got a high enough base frame rate, enabling frame generation can massively improve performance while only adding a negligible amount of input latency; you might not even perceive it. This can enhance your in-game experience and allow you to play said games at your monitor's native refresh rate.

Frame generation can also mask CPU stuttering, making it unnoticeable in CPU-demanding single-player games. After I enabled frame generation in S.T.A.L.K.E.R. 2, for instance, the CPU stuttering was all but gone.

Sure, I still noticed lower performance in settlements and increased input latency because my base frame rate was 50FPS or lower when in settlements. But when roaming around the Zone, frame generation eliminated CPU stuttering without noticeably increasing input latency.

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A CPU bottleneck can significantly reduce in-game performance. While upgrading the CPU might be the best course of action, there are a number of ways to reduce the CPU bottleneck or make it imperceptible. While your CPU might be ripe for a replacement, I recommend trying out these solutions before upgrading it.

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