Balancing PC Parts: Where Builds Bottleneck
A better part does not always mean a faster machine. Where a build stops scaling is mostly decided by the combination.
CPU and GPU balance
Higher resolution shifts work to the GPU and reduces CPU influence. The same parts behave differently at 1080p and 4K.
High frame rates at 1080p depend on the CPU. At 4K the GPU decides almost everything.
The configurator on this site shows both scores side by side; a large gap is where the build stops scaling.
| Resolution | Dominant part | Typical limit |
|---|---|---|
| 1920×1080 高フレームレート | CPU | CPUの単スレッド性能 |
| 2560×1440 | GPU寄り（CPUも効く） | GPUの演算性能 |
| 3840×2160 | GPU | GPUのVRAM量と帯域 |
Memory: channels and speed over capacity
Two sticks double memory bandwidth over one. 8GB×2 can beat a single 16GB stick, especially with integrated graphics.
Four sticks can force lower speeds. Two matched sticks is the safer choice for the same capacity.
DDR5 speeds vary widely at the same capacity. Paying for speed only helps in workloads that are bandwidth-bound.
Sizing the power supply
A common rule is 1.5–2× the calculated draw. Efficiency peaks near 50% load, and GPUs draw brief spikes far above their rating.
Those spikes trip protection circuits on units that look adequate on paper, causing reboots under load.
ATX 3.x units are designed for these spikes. For a high-end GPU, check that before adding capacity.
| Build | Guide | Notes |
|---|---|---|
| 内蔵GPUのみ | 400W前後 | 余裕は要らない |
| ミドルクラスGPU | 650〜750W | ATX 3.x が望ましい |
| ハイエンドGPU | 850〜1000W | ATX 3.x と 12V-2x6 端子を確認 |
| ハイエンドGPU + 多コアCPU | 1000W以上 | 分岐ケーブルを使わない |
Frequently asked questions
Should I spend on the CPU or the GPU?
It depends on resolution. CPU for high frame rates at 1080p, GPU at 4K, both at 1440p.
32GB or 64GB?
32GB is enough for gaming. 64GB helps with video editing or virtual machines. If unsure, use two sticks so you can add more later.