2x24gb vs 2x32gb DDR5 (Single vs Dual Rank ?)

[Buckster]

2x24gb 6000 CL30 kits seem to be about same price as 2x32gb but am I right in thinking 24gb modules more likely to be Single Rank and the 32gb ones Dual Rank. I've been looking at Corsair kits

Is there a negative if they are dual rank (running at EXPO settings) - or is it actually an advantage ?

2x24gb is probably plenty enough memory, but if 2x32gb is similar price may as well go for that - just was confused with the dual vs single rank

single rank modules (24gb ones) - more likely to overclock ?

most likely will be paired with a 9700k CPU.

I did consider 6400 CL32 for same price but I seem to have raid 6000 CL30 is probably optimum.

Any advice much appreciated thankyou

 

[FredFlint]

The 24GB sticks will be single rank and the 32GB will be dual rank as I don't think the 32Gbit dies are used for desktop kits yet. Dual rank kits will probably be harder on the memory controller. I would get the 64GB kit if the price is the same but I would probably run it at stock so...

 

[gupsterg]

2x24gb 6000 CL30 kits seem to be about same price as 2x32gb but am I right in thinking 24gb modules more likely to be Single Rank and the 32gb ones Dual Rank. I've been looking at Corsair kits

Is there a negative if they are dual rank (running at EXPO settings) - or is it actually an advantage ?

2x24gb is probably plenty enough memory, but if 2x32gb is similar price may as well go for that - just was confused with the dual vs single rank

single rank modules (24gb ones) - more likely to overclock ?

most likely will be paired with a 9700k CPU.

I did consider 6400 CL32 for same price but I seem to have raid 6000 CL30 is probably optimum.

Any advice much appreciated thankyou

Go 2x32GB.

Dual 32-bit subchannels​

DDR5 splits the memory module into two independent 32-bit addressable subchannels to increase efficiency and lower the latencies of data accesses for the memory controller. The data width of the DDR5 module is still 64-bit. However, breaking it down into two 32-bit addressable channels increases overall performance. For server-class memory (RDIMMs), 8-bits are added to each subchannel for ECC support for a total of 40-bits per subchannel, or 80-bits per rank. Dual rank modules feature four 32-bit subchannels.

Source for quote is Kingston DDR5 blog, didn't wish to link as they sell tech and dunno if against rules.

As you are talking about EXPO, the 9700K must mean 9700X, then translate this post via google/chrome, link. The guy knows tech.

 

[Minstadave]

2x32GB - 2 dual rank modules, will run fine but you won't be able to add more.

2x24GB - 2 single rank modules, value isn't as good, you could add a further 2x24GB modules.in future if you need more RAM as 4 single rank isn't as tough on the memory controller as 4 dual rank.

24GB modules will typically hit higher speeds when overclocking but that's largely pointless on AM5.

 

[pre]

Just be aware that running two separate kits of same speed is, unfortunately, not the same as running 4 sticks from the same kit if you are at all concerned about running at rated XMP speeds. Most likely you will need to underclock or tweak some what.

 

[gupsterg]

Putting aside CPU IMC, most motherboards are not T-Topology for RAM tracing, most are Daisy Chain; Daisy chain favours 1 dimm per channel.

Besides what I've read by shares, my own experience on few boards, running 2 dimms per channel is always tougher than 1 dimm per channel, regardless of single rank or dual rank.

I would always opt for 1DPC DR vs 2DPC SR.

 

[Buckster]

thanks very much for all of your replies much appreciated

it seems if running at stock then it's a no brainer - 2x32gb

but if I was to overclock the memory a bit I might be better off with the 2x24gb ? which if Corsair CL30 could be Single Sided M-Die ?

and yes sorry meant the 9700x. It seems to react better to higher clocked memory hence the wonder if I were to take a chance on 2x24gb to see if I can clock it (and the CPU memory interface) to beyond 6000

9700x seems to in tests scale better with memory >6000 than say 7800x3d which doesn't need it

the only game I'm to play that may require >32gb is FS2024 - it seems 32gb is right on the edge, hence why some tests seem to show much smoother experience with 64gb. I'm thinking though 48gb would be plenty

 

[gupsterg]

TPU used a 9950X+RTX 4090 and 2x16GB SR, gaming memory scaling results start here. I'd be surprised if a 9700X scales differently.

The Corsair 6000MHz CL30 2x24GB kit you mention should be SK Hynix M die.

 

[Buckster]

thanks very much I'll take a look at the link

it's odd that there seems to be quite a difference in a good few benchmark videos of FS2020/FS2024 - as in the videos you can see whether 32gb or 64gb the game is only using 32gb - BUT when you do say an external rotate/pan round the plane looking at the scenery the 32gb seems to stutter quite a lot, yet 64gb smooth. both showing same amount of memory used though.

maybe although only 32gb is being used the 64gb allows for "space" for the new stuff to be appended into the memory in parallel to un-used being removed from memory, and 32gb doesn't lend to that luxury ? not sure its a bit odd

 

[FredFlint]

thanks very much I'll take a look at the link

it's odd that there seems to be quite a difference in a good few benchmark videos of FS2020/FS2024 - as in the videos you can see whether 32gb or 64gb the game is only using 32gb - BUT when you do say an external rotate/pan round the plane looking at the scenery the 32gb seems to stutter quite a lot, yet 64gb smooth. both showing same amount of memory used though.

maybe although only 32gb is being used the 64gb allows for "space" for the new stuff to be appended into the memory in parallel to un-used being removed from memory, and 32gb doesn't lend to that luxury ? not sure its a bit odd

I used 64GB DDR4 for years, my new PC has 32GB DDR5 and it was a noticeable drop even though I mostly use < 32GB. Windows caches everything, this means re-loading things is a lot faster as it has a good chance of still been in RAM.