Reddit mentions of G.Skill Ripjaws V Series 16GB (2 x 8GB) 288-Pin DDR4 SDRAM DDR4 2666 Desktop Memory Model F4-2666C15D-16GVR

>Mhz really doesn't matter at all
>
>CAS latency

How does that even fit into the same message? You're completely wrong.

TL;DR. No, the RAM clock means a lot. Detailed explanation with examples and math below.

Your comparison to cars is also completely off the mark. To even bring it to something remotely correct, you have to account for the different cars, where slower RAM is an industrial truck running in higher gear, whereas the faster RAM is a sports supercar running 1 gear below the truck, so a truck in 4th gear with medium RPM against a supercar in 3rd gear with high RPM, going in a straight line on a completely flat asphalt road. Want to take a guess which one would win?

I'll even ignore the fact that higher-clocked RAM often has same CAS latency than lower-clocked RAM for the sake of argument.

So here's an explanation of how Mhz and CAS latency really work, which illustrates this point. First off, CAS latency is literally measured in memory cycles, which are measured in Mhz. I'll operate with nanoseconds in my calculations, so Mhz will be translated to Ghz (1Ghz is 10\^9 hz, while 1ns=10\^-9 sec) for easier-to-read numbers.

Say you have a typical 3200Mhz RAM stick (16gb, 75$) with 16 CAS latency. Keeping in mind that the bandwidth for memory commands operate at half the spec clock, we come to 3200Mhz for data transfer, but only 1600Mhz (1600 million per second, or 1.6 billion) for memory commands. Time for one full cycle is thus 1/1600000000 = 0.625ns. Then we multiply that value by the CAS latency number to translate cycles from latency to seconds: 0.625 * 16 = 10ns. This is the real latency of such a stick.

For comparison, let's take this G.Skill memory set (16gb, 70$ - I couldn't find faster) with 2666Mhz and 15 CAS latency. Doing the same procedure, we get 1.333Ghz clock for command interface, full cycle time of 1/1333000000 = 0.750ns, and finally the real latency of 0.750 * 15 = 11.25ns.

If you take RAM with even higher clocks, the difference will be even bigger, for instance RAM with 3600Mhz and 19 CAS latency (10.6ns) would still be faster than 2666Mhz 15 CAS one (11.25ns).

Not only is the first set clocked higher, which brings additional advantages with certain CPU models, especially Ryzen, it also has lower actual latency despite having higher CAS latency. It is literally better in every single aspect that concerns performance. To match that at all, the slower 2666Mhz stick would need 13 CAS latency (that would bring it to 9.75ns), and I couldn't find memory like that. Or in reverse, to make the higher-clocked memory run as slow as the lower-clocked one, you would need 17 CAS latency (would bring it to 11.33ns), which would make the real latency only marginally bigger (we're talking about fractions of a nanosecond here) while having significantly higher throughput, so it would still be faster overall.

So yeah, I would say Mhz of the RAM means a whole lot, while it is actually hard to find higher-clocked RAM with CAS latency bad enough to make it slower than lower-clocked RAM.

Is this likely a scam? Ram at half price with seller at 1 rating.

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what is the difference between this and this?