Asus Z390 i9 9990K ou i7 9700K
Asus Z390 i9 9990K ou i7 9700K
You're asking about the purpose of additional RAM. It helps for performance and multitasking.
Aim for the best possible outcome, though I think the 9900k price tag is high. It might be smarter to sell everything together and purchase a 10700KF/Z490 when it's on sale. This depends on what's available in your area.
Intel's sweet spot sits around 4000MHz CL16. B-Die modules with 3600 16-16-16-36 ratings can hit 4000 under the same settings with a slight voltage adjustment. For top performance, consider two 8GB single-rank drives.