If you examine a timeline of computer specs, you'll see what combinations worked. Over the decades, interrelated components were made to work at increasingly faster speeds, and to work together reliably, and to be on a par in terms of financial and market considerations.
RAM speed increased with RAM size. Etc.
Static RAM is older and slower than dynamic ram.
You can overclock a cpu, however speed should be slower if heatsinking is insufficient. Processors have limits as to the size of RAM they can access.
There is a spec for bus speed. This may be slower than the processor.
RAM has a certain spec for how quickly it responds (in uSec). The refresh routines also takes a certain amount of time.
Computer specs state the minimum speed which the ram should have. Specs warn against installing slower ram, because then the cpu must wait an extra cycle for every ram call to respond. Faster ram is okay in that sense but there's little benefit in paying more for increasingly faster ram because you don't gain more cpu speed by increasingly faster ram.