14/06/2024
What are bottlenecks and how to avoid them
Discussion
A good piece of advice when building a PC is to have a balanced part list, else bottlenecks may occur.
A bottleneck happens when a faster component is limited by another. This refers to CPU, GPU, RAM.
There is a point where, keeping one part the same, having a faster another part is not helpful at all.
Many people build a PC for gaming. A too fast CPU with a too slow GPU (or the reverse) is usually bad.
Instead of thinking about a single performance metric (like FPS), we can use one metric for each part.
We can define a CPU FPS and a GPU FPS, the actual FPS being always the lower value, never the upper.
CPU FPS = FPS when the CPU is the bottleneck - No matter how fast the GPU is, this is the maximum.
GPU FPS = FPS when the GPU is the bottleneck - No matter how fast the CPU is, this is the maximum.
This may be an oversimplification, but the statements above are true within a small margin of error.
CPU FPS increases with the single core performance and with the core count up to a limit (now 6 - 8).
GPU FPS increases when the GPU is better and when the graphical settings (+resolution) are lowered.
In order to avoid bottlenecks when gaming, here are some rules for deciding between CPU and GPU:
The more demanding the game is, the more a faster GPU is needed and the less a faster CPU.
Actually both are needed, but if the GPU is weak, the game is going to be almost unplayable.
AAA games are more demanding than e-sports, newer games are more demanding as well.
The higher the graphical settings are, the more a faster GPU is needed and the less a faster CPU.
Resolution is included in graphical settings and it has values like: 1080p, 1440p and 4K.
1080p = 1920 x 1080, 1440p = 2560 x 1440, 4K = 3840 x 2160, others are virtually unused.
(!) Some games (like simulation ones) are not graphically focused, they need a strong CPU.
Keep in mind that 1440p is much closer to 1080p than to 4K. The rule: 4K gaming is GPU bottlenecked.
How many pixels? 1080p = 2 073 600 pixels, 1440p = 3 686 400 pixels, 4K (2160p) = 8 294 400 pixels.
Sometimes a bottleneck occurs between the CPU and the RAM, particularly when the RAM is slow.
First of all, 3200 MHz CL 16 is the sweet spot and it should run at this speed on many new systems.
If gaming using an integrated GPU, don't get slower RAM because RAM is a huge bottleneck here.
The final rule: Always search for benchmarks. Try to find many sources to be sure of the performance.
