RAM: Speed vs Latency

[KhaderKh]

Hi,

 

I know this might be repeated topic, but I read so much and watch youtube videos and its getting more confusing due to different results I see from these benchmarks.

 

My Rig:

i7 9700KF @5.00Ghz @1.3v

Asus Z390m Prime

2x8GB DDR4 HyperX Predator OC to 3400mhz @1.35v, CL 16,18,18, 38

RTX 2080 Super

2560x1440 Monitor

 

Some say that CL is more important, other RAM speed, some say that for intel 3000mhz is enough, others say intel CPU wont run RAM more than 2666mhz as advertised on their website.!!!

 

 

[Haro]

1. both matter, some workloads prefer bandwidth over latency and others prefer latency over bandwidth. but both are important, for example, a 3200 cl16 kit performs about the same when it comes to latency as a 3600 cl18 kit. 

1 hour ago, KhaderKh said:

others say intel CPU wont run RAM more than 2666mhz as advertised on their website.!!!

That's just wrong, 2666 is the base speed for the imc, meaning that anything over that is an overclock to the imc and is techincally not guaranteed, but assuming you are using a Z series board (which you are) you can run higher speeds.  

[porina]

You got fast ram already, just run it as such and don't worry about it. Most things are not very ram bandwidth limited so only see modest changes in performance with faster ram. 

 

Different workloads scale differently with speed and/or latency. Speed will also affect latency. Generally I'd go for the fastest without paying silly money for it, with timings a very much secondary consideration. Around 3000 is great for a value build, above that is better but not essential.

 

On Intel side, there is some complication with compatibility. Generally you can't run ram above the CPU's supported speed without a Z chipset. AMD systems have different considerations which impact ram choice, if you really want to squeeze more performance out of it.

[Bombastinator]

4 minutes ago, KhaderKh said:

Hi,

 

I know this might be repeated topic, but I read so much and watch youtube videos and its getting more confusing due to different results I see from these benchmarks.

 

My Rig:

i7 9700KF @5.00Ghz @1.3v

Asus Z390m Prime

2x8GB DDR4 HyperX Predator OC to 3400mhz @1.35v, CL 16,18,18, 38

RTX 2080 Super

2560x1440 Monitor

 

Some say that CL is more important, other RAM speed, some say that for intel 3000mhz is enough, others say intel CPU wont run RAM more than 2666mhz as advertised on their website.!!!

 

 

The deal is different editions of different CPUs are more or less able to take advantage of ram speed increases. As a result for some intel versions (8th gen and below?) there isn’t a good reason to pay more money for faster ram because not much benefit can be gained. Faster ram costs more money, so it can become a false economy.  Faster ram is still faster, so one of these CPUs that uses it less efficiently would still get faster of memory was all the same price, but currently it’s not.  If some day the only ddr4 is 4000mhz for example (something I expect to eventually come to pass) a chip that doesn’t use faster memory well can still use it fine.

[Mateyyy]

6 minutes ago, KhaderKh said:

Some say that CL is more important, other RAM speed, some say that for intel 3000mhz is enough, others say intel CPU wont run RAM more than 2666mhz as advertised on their website.!!!

Ryzen tends to benefit more from lower latency, Intel tends to benefit more from higher frequency, but ultimately it's a balancing act regardless of platform.

 

I don't see anything to worry about in your case - 3400 CL16 is fast enough that you won't see a notable benefit in terms of performance with a faster memory kit in most real-world workloads.

 

2666MHz is what the IMC on your 9700KF is rated for. Anything over that is considered an overclock, and not necessarily guaranteed to be obtainable (but for a Coffee Lake IMC to not handle anything more than 2666MHz, it must be seriously borked).

[KhaderKh]

Thank you all