Will adding a second, RGB DDR5 kit make all four RAM sticks work together?

The RGB difference itself doesn't matter, and four modules can work together. However, two separate kits—even if they have the same advertised speed, timings, and voltage—aren't guaranteed to behave like one factory-matched four-stick kit. DDR5 is especially sensitive to this, so you may need to lower the memory speed or relax the timings to get a stable boot. On AM5 systems, four sticks commonly require dropping from 6000 MT/s to something around 5200–5600 MT/s, and some CPU and motherboard combinations may struggle even more.

It may work at the advertised settings, but treat that as luck rather than a guarantee. Intel platforms often handle four DDR5 sticks a little better, while AM5 generally prefers two modules. If you try the extra kit, enable the memory profile only after confirming the system is stable, and be prepared to run a lower speed or test manually for errors.

Check the full specifications rather than just the capacity and speed. The timings, voltage, memory chips, and motherboard support list can all matter, and two kits with the same model family may still use different memory ICs. Buying a single 64GB kit designed as four matched modules is the safer option if you need guaranteed capacity and stability.