I read somewhere that Ryzen can take advantage of higher RAM frequency. But is this independent of CL?
So just to check, if I have two RAMs of different frequency but similar overall timings, will the higher freq RAM give better performance?
E.g -
RAM 1: 2133MHz at CL14 = 152
RAM 2: 2400MHz at CL16 = 150
Almost the same timings, is RAM 2 going to perform better?
Are you dividing clockspeed with CL?
Column Access Strobe (CAS) latency, or CL, is the delay time between the moment a memory controller tells the memory module to access a particular memory column on a RAM module, and the moment the data from the given array location is available on the module's output pins.
Before we start, note that clock refers to I/O bus clock. Data rate is double of I/O bus clock due to DDR. The marketing number e.g. DDR-2133 is data rate.
So DDR-2133 @ CL14 results in slightly less time between data request and data out. (13.125ns, vs DDR-2400 which is 13.333ns)
HOWEVER, time is also needed to transfer data from RAM to CPU. And that is where higher clockspeed helps. For example, to transfer 1kByte with a 128-bit bus requires 32 clock cycles. This will take 30ns with DDR-2133 ram. But with DDR-2400 RAM, but only 26.66ns with DDR-2400.
CAS latency in ns is usually a fixed value based on the quality of the chip (or design), that's why you are forced to use a higher CL with higher clockspeed. However, if you make the latency in terms of ns equal, higher clockspeed is always better.
