I'm putting together a budget AM4 system using mostly inexpensive second-hand parts. I bought a Corsair memory kit but mistakenly thought it was 2×8GB when it turned out to be 2×4GB. I can buy another two 4GB sticks cheaply, giving me 16GB in a 4×4GB configuration, and my motherboard supports four modules. Are there any meaningful drawbacks besides having less room for future upgrades? Would it be better to sell the current kit and buy 2×8GB instead?
4 Answers
Four DDR4 sticks should work perfectly well on AM4. The main things to watch are matching the speed, timings, and voltage as closely as possible. If the kits differ, the system will generally use settings that all four modules can handle.
A 4×4GB setup is a reasonable way to reach 16GB cheaply. You probably won’t notice a performance difference compared with 2×8GB outside of benchmarks. Two sticks are a little simpler and leave room for upgrading, so 2×8GB is better if the price difference is small, but there’s no urgent reason to replace the kit.
The biggest potential downside is reduced overclocking headroom. Four modules can be a little harder on the memory controller than two, especially if you’re aiming for very high speeds. For normal DDR4 speeds around 3000–3200 MT/s, though, it usually isn’t a concern. AM4 is generally quite reliable with four sticks.
If you combine a 2800-speed pair with a 3000-speed pair, the memory will normally run all four sticks at the slower compatible setting, likely around 2800 unless you manually tune it. Having the same model and specifications is preferable, but mixing similar Corsair Vengeance LPX kits often works fine. Test it with a memory stability tool after installing them.

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