Does RAM frequency matter?

[Benji]

I'm building my first unraid server so I'm doing a lot of research on parts. I plan on using an i5-11400 as the CPU, I want the iGPU for PLEX.

 

Currently, I'm wondering what RAM to get. What's the consensus on ram speeds? The CPU I have officially supports up to 3200Mhz, obviously you can go higher with overclocking. However, as far as I'm aware, with DDR4, anything over 2133Mhz using XMP is still technically overclocking. This seems to go against the general opinion I've read that overclocking in a server is bad as it may introduce instability.

 

Do people use XMP and it's fine or do some of you leave it at 2133Mhz? The upside to 2133Mhz of course is it's cheaper and runs at 1.2v instead of 1.35v, however, you're losing a lot of speed. Does it matter?

 

I'd appreciate any thoughts or advice people have on the matter.

 

Many thanks.

Edited March 25, 2021 by Benji

[Squid]

All overclocks (XMP included) introduce instability into any system and should be avoided.

[uldise]

Depends on hardware generation. i just setup AMD Epyc Rome server with 3200MHz DDR4 - work by default, a this is recommended and supported RAM speed for this system.  

[JorgeB]

8 hours ago, Benji said:

anything over 2133Mhz using XMP is still technically overclocking.

You can buy RAM with JEDEC default settings for 3200, just an example:

 

https://www.kingston.com/dataSheets/KVR32N22S6_8.pdf

 

"Gamer" DIMMs usually default to 2133 or 2400 and you need to use the XMP profiles to set it higher, e.g.:

 

https://www.kingston.com/dataSheets/HX432C16FB3_8.pdf

 

I wouldn't really call that overclocking, though you can still I can do it since they usually use higher voltage because of the tighter timings, but worse would be using for example 3600 RAM on a CPU that officially only supports up to 3200.

[Vr2Io]

In practical usage I haven't got big difference of dual / quad channel from 1866MT to 3000MT, so I don't care those speed much ( but heat generate in 1.35 was significant )

 

But a new add repurpose machine have major slow down on 10G network performance, the only difference is it run in single channel 2666MT, I am waiting a memory module RMA back then will got the answer.

Edited March 25, 2021 by Vr2Io

[binzhu1070]

Question then, I have ram labeled 3600 c18 I see Mobo official support is 3200, is it ok to run like that or does has to be the default 2133? I see somewhere else mentioning 3200is ok but want to cross check.

 

Also, the MSI memory preset set the ram at c16 when speed at 3200, is that a problem? Do I need to dial it back to c18?

 

 

 

[ChatNoir]

3 hours ago, binzhu1070 said:

Question then, I have ram labeled 3600 c18 I see Mobo official support is 3200, is it ok to run like that or does has to be the default 2133? I see somewhere else mentioning 3200is ok but want to cross check.

 

Also, the MSI memory preset set the ram at c16 when speed at 3200, is that a problem? Do I need to dial it back to c18?

The memory stick capability is irrelevant if all the other components do not support it. By that I mean the MB but more importantly the memory controller (in the CPU).

 

In any case, 3600 is way overclocked for memory controllers on any plateform. Intel tends to support between 2400 and 2933 on recent chips and AMD around 3200.

Those general values will depend on the specific CPU model, the memory configuration, etc.

 

Remember that all everything on a computer goes through RAM. And unsupported speed has a higher tendency to corrupt some data.

If the data is corrupted in RAM, it will be written like that and there is nothing Unraid can do to correct that.

 

In any case, except for very specifc tasks, memory speed has a limited impact on raw performance, why take the risk ?