@TINGRE, those were the data rates, "clock speeds" or MT/s.
At 3000 MT/s, dual channel DDR4 gives you about 38 GB/s.
With my 3200 C14 dual-channel kit and Ryzen 7, I get about 47 GB/s actual bandwidth in AIDA64 benchmark (it's higher than the 41 GB/s theoretical due to caches and pre-fetches), and a latency of about 72.5ns. Also, latency is important for many things including games.
If you just wanted lots of cheap RAM then an old workstation board with DDR3 support is a good bet, but lots of people care about IPC, clock speeds, modern instruction sets and core counts too.