DDR5 pricing has gotten extremely high, and I'm finishing a gaming PC with a Ryzen 7 7800X3D and Radeon RX 9070 XT for 1440p gaming. I'm comparing three 32GB kits: a €310 2×16GB DDR5-5600 CL46 Crucial Pro kit, a €380 used 2×16GB DDR5-6400 CL32 kit using Hynix A-die with EXPO/XMP, and a €440 brand-new 2×16GB DDR5-6400 CL32 kit. Is DDR5-5600 CL46 likely to cause any stability, 1% low, frametime, or EXPO problems, or is it simply slower? I'm leaning toward the cheaper kit because the price difference is significant, but I don't want to regret saving money. Would you pay the extra €70 for the used 6400 CL32 kit or €130 for the new one?
4 Answers
DDR5-5600 CL46 is noticeably looser than the other options, so a few games—especially ones that are CPU- or memory-sensitive—could show lower average FPS or 1% lows. Still, it is not a compatibility problem by itself. The main tradeoff is performance, not stability or game support.
I would choose the 5600 CL46 kit if the €130 difference matters to you. It will run your games normally, and the 7800X3D’s large cache reduces the impact of slower RAM. The faster kit is better, but it is an optional performance upgrade rather than something the CPU requires.
The 5600 kit should work fine and won’t suddenly make the 7800X3D perform badly. X3D processors are generally less sensitive to memory speed in games than some other CPUs, so the difference between these kits is often modest. At current prices, I’d be comfortable choosing the €310 option unless you specifically want to maximize every last frame.
If you’re worried about buyer’s remorse, the faster kit could always be run at a lower speed. That gives you more flexibility, assuming the used modules are fully tested.
The Hynix A-die 6400 CL32 kit has better overclocking and timing potential, which could be useful later. However, don’t assume every 7800X3D memory controller will run DDR5-6400 perfectly. Many AM5 systems are happiest around DDR5-6000, and you may need to lower the speed or adjust settings for a stable 1:1 configuration.
That’s why the used kit is only worth considering if you can verify that it works properly and are comfortable testing it. Paying more for a kit that ends up running at 6000 may not provide much real-world benefit.
Some games benefit more from tuned memory than others, but the improvement with an X3D chip is usually not large enough to justify a huge premium unless you care about benchmarking or want extra headroom.