Is Your CPU Bottlenecking Your GPU? How to Check
Low FPS despite a powerful GPU? Your CPU might be the problem. Here's how to find out and what to do about it.
What is a bottleneck?
A bottleneck happens when one component in your PC can’t keep up with another, limiting overall performance. In gaming, the most common bottleneck is either the CPU holding back the GPU, or the GPU holding back the CPU.
When your CPU is bottlenecking your GPU, the GPU is sitting partially idle waiting for the CPU to feed it work. You’re paying for GPU performance you’re not getting.
CPU bottleneck vs GPU bottleneck — what’s the difference?
CPU bottleneck: The CPU can’t prepare frames fast enough for the GPU to render. The GPU usage sits below 95–99% while the CPU usage is at or near 100%. Frame rates are lower than your GPU should be capable of, and the problem gets worse at lower resolutions.
GPU bottleneck: The GPU is the limiting factor — it’s working at 99–100% and can’t render frames any faster. This is actually what you want. A GPU running at full utilization means you’re getting everything out of it. Frame rates improve if you lower settings or resolution.
The goal is to have your GPU be the bottleneck, not your CPU.
How to check if your CPU is bottlenecking your GPU
Method 1 — Check GPU and CPU usage in-game (free, most reliable)
This is the most accurate method. You need real usage numbers while actually playing.
Using MSI Afterburner + RivaTuner (free):
- Download and install MSI Afterburner and RivaTuner Statistics Server (installs alongside it)
- In Afterburner, go to Settings → Monitoring
- Enable CPU usage (all cores or per core), GPU usage, and framerate
- Set them to show in the on-screen display
- Launch your game and play for a few minutes in a demanding area
What the numbers mean:
| GPU usage | CPU usage | Diagnosis |
|---|---|---|
| 95–99% | Below 80% | Healthy — GPU is the bottleneck, as intended |
| Below 85% | 90–100% | CPU bottleneck — CPU is limiting your GPU |
| Below 85% | Below 80% | Something else — check temps, RAM, or driver issues |
| 99% | 99% | Both maxed — you need upgrades across the board |
A CPU bottleneck is confirmed when GPU usage is consistently below 85–90% while CPU usage is pinned at or near 100%.
Method 2 — The resolution test
A quick way to confirm a CPU bottleneck without any tools:
- Note your current FPS at your normal resolution (e.g. 1080p)
- Increase resolution to 1440p or 4K and note FPS again
If FPS drops significantly when you raise resolution, the GPU is the bottleneck — more pixels = more GPU work. This is normal behavior.
If FPS barely changes when you raise resolution, the CPU is the bottleneck — the GPU had headroom either way and the CPU is the ceiling.
Common causes of CPU bottlenecks
Mismatched components. Pairing a high-end GPU with a weak CPU is the most common cause. An RTX 5070 paired with a quad-core CPU from 2016 will bottleneck badly regardless of resolution or settings.
Low core count. Modern games increasingly use 6–8 cores. A dual or quad-core CPU will bottleneck in newer titles even if it was fine a few years ago.
Low clock speeds. Gaming is heavily dependent on single-core performance — a CPU with high core counts but low clock speeds (below 3.5GHz boost) can still bottleneck in games that don’t parallelise well.
High framerate gaming. CPU bottlenecks are most visible at high framerates and low resolutions. If you’re trying to hit 300fps in Valorant on a 360Hz monitor, you need a fast CPU. At 60fps the same CPU might be fine.
Background processes. Browsers, Discord, streaming software, and Windows updates all consume CPU cycles. Close non-essential programs before testing.
How much bottleneck is acceptable?
No pairing is perfectly balanced — some degree of bottleneck always exists. The question is how much.
A 5–10% bottleneck is normal and not worth worrying about. You’d need to spend significantly more money to eliminate it, and the real-world FPS difference is negligible.
A 15–25% bottleneck starts to hurt. You’re leaving meaningful performance on the table.
Anything above 25% means your CPU is a serious limiting factor and an upgrade will have a noticeable impact.
Does resolution affect bottlenecking?
Yes, significantly. Resolution is one of the most important variables.
1080p is the most CPU-demanding resolution for gaming. With fewer pixels to render, the GPU finishes frames quickly and demands more from the CPU. CPU bottlenecks are most visible at 1080p.
1440p shifts more work to the GPU and reduces CPU bottleneck severity. Most mid-range CPU and GPU pairings are well-balanced at 1440p.
4K is almost always GPU-limited. Even weak CPUs rarely bottleneck at 4K because the GPU is working so hard rendering the increased pixel count that it becomes the limiting factor.
If you’re gaming at 1080p and experiencing a CPU bottleneck, switching to 1440p will often reduce or eliminate it without any hardware changes.
Common CPU and GPU pairings — are they balanced?
| CPU | GPU | Resolution | Verdict |
|---|---|---|---|
| Ryzen 5 5500 | Arc B580 | 1080p | Mild bottleneck at high framerates |
| Ryzen 5 5600 | RTX 5060 | 1080p | Well balanced |
| Ryzen 5 5600 | RTX 5070 | 1080p | Moderate CPU bottleneck |
| Ryzen 5 9600X | RTX 5070 | 1440p | Well balanced |
| Ryzen 7 9800X3D | RTX 5090 | 1440p | Well balanced |
| Core i5-12400F | RTX 5070 | 1080p | Moderate CPU bottleneck |
| Core i5-12400F | Arc B580 | 1080p | Well balanced |
How to fix a CPU bottleneck
Option 1 — Change your settings (free)
Before spending money, try these:
- Increase resolution — shifts load to the GPU
- Enable ray tracing — GPU-heavy, reduces CPU load proportionally
- Increase graphical settings — higher settings = more GPU work = less CPU bottleneck
- Cap your framerate — if you’re targeting 144fps, cap at 144. Chasing uncapped frames maximises CPU demand.
- Close background apps — free up CPU cycles for the game
Option 2 — Upgrade your CPU
If settings changes aren’t enough, a CPU upgrade is the answer. For AM4 boards, this is often affordable without replacing the motherboard.
Best CPU upgrades for common AM4 boards:
| Current CPU | Best upgrade | Why |
|---|---|---|
| Ryzen 5 1600 / 2600 | Ryzen 5 5600 | Massive single-core jump, same socket |
| Ryzen 5 3600 | Ryzen 7 5800X3D | Best gaming CPU for AM4 |
| Ryzen 5 5500 | Ryzen 7 5800X3D | Best gaming CPU for AM4 |
| Ryzen 5 5600 | Ryzen 7 5800X3D | Worth it if gaming at high framerates |
The Ryzen 7 5800X3D is the best gaming CPU AM4 will ever get — if your board supports it and you’re CPU bottlenecked, it’s the upgrade. Read our AMD vs Intel comparison for more context on current CPU options.
For Intel LGA1700 boards, the Core i5-13600K or i7-13700K are strong upgrades if your board supports 13th gen. Check your motherboard’s CPU support list before buying.
Option 3 — Lower your resolution or framerate target
If you’re CPU bottlenecked at 1080p trying to hit 240fps, consider whether 1440p at 144fps would give you a better experience with your existing hardware. Often it does — and you avoid the upgrade cost entirely.
What about bottleneck calculators?
You’ve probably seen websites that let you enter a CPU and GPU and spit out a bottleneck percentage. Ignore them. These tools use synthetic benchmark ratios and don’t account for the game you’re playing, your resolution, your settings, your RAM speed, or your actual workload. They’re not useful.
The MSI Afterburner method above gives you real numbers from your actual system running your actual games. That’s the only bottleneck measurement that matters.
The bottom line
A CPU bottleneck means your GPU has unused performance capacity because the CPU can’t keep up. Check it with MSI Afterburner — GPU usage consistently below 85–90% while CPU is at 100% confirms it. The fix is usually raising your resolution, adjusting settings, or upgrading the CPU.
If you’re planning a new build and want to avoid bottlenecks from the start, check our build guides — every build has matched CPU and GPU pairings selected to avoid this problem.