I have an older PC with 32GB of DDR4 installed: two Corsair 8GB sticks rated at 3200MHz, plus two Kingston HyperX 8GB sticks—one rated at 2400MHz and the other at 3200MHz. The system currently runs all of the memory at the slowest compatible speed. I sometimes use more than 24GB, but I'm wondering whether removing the 2400MHz stick would be better overall. That would leave me with 24GB and potentially allow the memory to run around 3000–3200MHz, although the unmatched capacity may affect dual-channel operation. Games also seem to deliver lower-than-expected FPS even when CPU and GPU usage are only around 60%. Should I prioritize capacity or faster memory?
3 Answers
If the computer is stable and you occasionally use more than 24GB, keeping all 32GB may be the better practical choice. The system will generally run the memory at a common speed and may use part of the RAM in a less optimal channel configuration. Faster RAM can help, but the difference is usually much smaller than the impact of running out of memory and paging to disk. The easiest answer is to test both configurations with the same game or benchmark and keep whichever feels better.
You can try manually setting a moderate speed such as 2666–3000MHz, but mixed memory is not guaranteed to tolerate the advertised 3200MHz settings. Use conservative timings and voltage, and reset the BIOS if the system fails to boot. Since the 2400MHz module became unstable when overclocked, removing it and testing the remaining sticks at 3000MHz is a reasonable experiment. Also, CPU and GPU usage around 60% does not by itself prove that RAM speed is the bottleneck—check frame-time graphs, per-core CPU usage, VRAM, and whether the game is waiting on storage or another limit.
I tried increasing the slower module before, but the system reverted to a lower speed. After removing it, the remaining memory is currently running at 3000MHz, so I’ll compare game performance and stability before trying 3200MHz again.
With three 8GB sticks, the system can typically run 16GB in dual-channel mode and the remaining 8GB in single-channel mode when it is needed. Removing the 2400MHz stick could let the remaining memory run faster, but you would lose 8GB of capacity and still would not have a perfectly matched kit. If 24GB is enough for your normal workload, it is worth testing; if applications regularly exceed that, the extra capacity may matter more than the speed increase.
That makes sense. I’m going to compare the configurations instead of assuming the faster rating will automatically improve FPS.