What Is a CPU Bottleneck and How to Check for One
Updated 2026-10-04
A bottleneck is the part of your PC that limits the frame rate. In every system something is the slowest part. The question is whether it is the part you expected.
GPU bound and CPU bound
When the graphics card is the limit, GPU usage sits near 95 to 100% and the frame rate follows the card. That is normal and usually what you want. When the CPU is the limit, GPU usage drops well below that while one or more CPU threads run close to their maximum.
How to test
- Open a monitoring overlay such as MSI Afterburner or the one in your GPU driver.
- Play a demanding scene and read GPU usage and the busiest CPU thread.
- Lower the resolution. If the frame rate barely rises, the CPU is the limit. If it rises a lot, the GPU was the limit.
What helps
- If you are CPU bound, raise resolution or quality settings. This moves work to the GPU at no frame rate cost.
- Close background apps that use CPU time.
- Make sure memory runs in dual channel at its rated speed.
- Upgrade the CPU if the limit holds in the games you play.
Calculators and real games
A calculator estimates which part is more likely to limit a pairing. It cannot see your game, settings or drivers. Use the PC Bottleneck Calculator to plan, and the overlay test to confirm.