Question Ram Speed and timings:

[Swordkd]

So quick question, new build and atm I'm planning on an AMD X570 chipset motherboard, 6/8 core Ryzen 3000 series Cpu and this particular Ram: https://www.newegg.com/Product/Prod...-na-_-na&cm_sp=&AID=10446076&PID=3938566&SID= DDR4, 3000mhz 15-15-15-35 . My question is, how high of a CAS latency could I go with a faster mhz ram to actually have it perform better? I know that faster speeds with lower latency is better, but I don't know where the break even point is on speed vs. timings, and this set has some of the best timings I've seen at 3000mhz without spending a ton of money.

 

[TJ Hooker]

My question is, how high of a CAS latency could I go with a faster mhz ram to actually have it perform better?

Perform better than what? I'm not sure what "break even" point you're referring to.

That RAM would be fine. Although I don't see much point in picking out a kit now, just wait and see what the best deals are when Ryzen 3000 is out and you're ready to buy.

 

[Swordkd]

Well, at what point would a 2800mhz speed set with a lower latency and timings perform better than the set I listed, or 3200/3400/etc. with slower timings perform better?

 

[TJ Hooker]

Depends on what you're doing. Some things prefer higher bandwidth, some things prefer lower latency. Generally games prefer lower latency, but Ryzen in general likes higher memory frequencies because it speeds up the Infinity Fabric. There's no easy answer.

Latency for RAM is listed in # of clock cycles. To calculate real latency in nanoseconds, take that number, multiply by two, then divide my the memory speed (in GHz). So 3000 MHz CL15 has a real CAS latency of 10 ns. Which is equivalent to 2800 MHz CL14 in terms of CAS latency. Although current Ryzen CPUs don't support odd CAS latency values, so the CL15 kit would might only run at CL16 (unless you were able to get it to run stably at CL14).

 

[Swordkd]

ok, that's type of answer I was looking for. So I can look for 3200 with CL of 16 and get similar performance, or better because of the oddity(see what I did there?). Thank you.