4000mhz cl 17 vs 3600mhz cl 16

[Norppa77]

Hi i am building gaming computer and need advice on my memory. First memory is G.skill Trident Z Neo DDR4 3600MHz (16-16-16-36)F4-3600C16Q-32GTZN. Second memory is G.skill Trident Z RGB, DDR4 4000MHz (17-17-17-37)F4-4000C17D-16GTZR getting 2 sets of these. There is price difference but both are inside my budget. Which one i should choose? motherboard is ROG Crosshair VIII Hero and processor amd 5950x.

[Mateyyy]

I'd go for the 3600 CL16 kit, unless the 4000 one is somehow cheaper.

 

4000 CL17 isn't really that much better than 3600 CL16 in terms of latency, and your CPU most likely won't be able to hit 2000MHz on the FCLK, which would drop performance drastically or would require you to downclock the RAM.

[8-Bit Ninja]

There's no real benefit in Zen 3 past 3600mhz, so go with the slightly cheaper (I'm assuming), slightly lower latency Trident RGB

[Eigenvektor]

I'd go with the 3600 MT/s one, since this is more likely to work out of the box and there's diminishing returns the faster you go.

 

There's also the (potential) issue that normally Infinity Fabric, which is needed for core-to-core communication, will usually only run 1:1 with memory speed up to around 1800 MHz (~3600 MT/s effective). Beyond that it will switch to 1:2, unless you overclock IF as well. If you have many core heavy applications this could actually hinder performance. Though Ryzen 5xxx can apparently go up ~2000 MHz on the IF, which would match the 4000 MT/s RAM.

 

4 minutes ago, 8-Bit Ninja said:

slightly lower latency Trident RGB

Keep in mind that CAS latency is measured in clock cycles. The 4000 MHz RAM actually has (slightly) lower latency.

CL16 @ 3600 -> 8.88 nanoseconds

CL17 @ 4000 -> 8.5 nanoseconds

[Norppa77]

I went for the 3600mhz. thx for the advises.