I got 3600 MHz ram with C18. Does that mean it won't be able to run at 3600 MHz? If so, would 3200 MHz ram with C16 latency be faster for the 3900x?
I bought the 3600 mhz C18 ram for $66 with a black friday deal. Should I return it and buy 3200 MHz C16 RAM for ($5-10) more (costs more because there aren't any deals now)?
as I said, the timings and speed are connected.
3200MHz with CL16 is the same as 3600MHz CL18 (in regards to the CAS Latency specifically) but the 3600MHz speed in and of itself is faster if you can run it at that speed or close to it.
But getting RAM to run at speeds higher than 3200MHz with Ryzen can be a chore sometimes depending what CPU you have, and what motherboard you have and whether or not the RAM is on the QVL or not.
But also as stated, you get diminishing returns on anything higher than 3200MHz.
Overall performance of the CPU and the system and games becomes less exponential the higher above 3200MHz you go.
So while overall performance will be better, it won't be a ton better.
If you are worried about it, and have the option to get your money back and instead get the 3200MHz RAM, then do that.
But make sure it's not some cheapo RAM and that it will run at it's rated speed on your system.
Overall I would say since you bought it, just stick with it.
If you can get it to run at it's speed or close to it either with XMP/DOCP profiles, or by manually dialing in the speed, timings, and voltage, then great, but if not, then you can still at least run it at 3200MHz with tighter timings, or dial in a clock speed in between the two speeds at custom timings, or just have it on hand for when you upgrade CPU and mobo in the future and can get it to run at it's rated speed then (assuming you can't get it to run that speed on your current hardware)