Confused on what memory to buy

Reb71

Reb71

Reb71

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Ok so building a new system. I've never gone for AMD before but went for AMD R 5900X paired with Asus Rog Strix X570-F MB. I'm confused on what memory to get.

I want 32GB and I'm looking at 2x16gb or 4x8gb sets at 3200Mhz or 3600Mhz. I'm not really looking to overclock memory, just want it to work in stable fashion for a sensible price. I can't see me ever needing to upgrade this to 64gb since by then I'd be buying a new machine with DDR5 etc.

Issue is I'm reading conflicting things on web about what is optimal memory to get
1. Seems dual rank 2x16gb is ideal but these days a lot of cheaper 2x16gb sets seem to be single rank.
2. 4x8gb is often a good option but some argue that causes performance drag with "daisychain topology" MBs like X570F.
3. Also hear that 4x8gb at 3600Mhz is "unstable" on AMD MBs. Is that really true?
4. 3600Mhz is "sweet spot" but I don't quite see why 3600MHz CL18 is going to be better than 3600Mhz CL16?

Any clarity on this would be appreciated since I'm going round in circles and I suspect it probably won't matter! Also any recommendations for 32gb sets in the sub £200 area would be great
 
1. Dual rank does have a definitive (if not huge) performance advantage
2. Possibly, but I wouldn’t worry too much about it
3. I had issues running four DIMMs, didn’t resolve properly until I’d tried three kits. However recent AGESA updates have made things more stable for most, so I wouldn’t worry too much.
4. It isn’t better, definitely the case that lower case latency is a good thing

Overall I’d recommend going for any dual rank, 3600 MHz 2x16 kit, or a 4x8 kit that’s AMD tested.

Low latency is a definite plus and TBH most can get their memory up to 3800 with a 1:1 fclk without fiddling with voltages etc so 3800/4000 kits might not be a bad idea if you don’t mind a quick trip to bios.
 
Thanks for the replies. So dual rank matters, topology less so, and the 3600Mhz instability is less of an issue.
On 4. I made a dumb typo. Cleary if they are both 3600 and it's CL18 vs CL16 then the lower Cl16 is better! I meant to say "I don't quite see why 3600MHz CL18 is going to be better than 3200Mhz CL16?" i.e if both have a latency of 10ns, is the 3600 CL18 appreciably better than 3200 CL16?

I'm just concerned that far more 3600 CL16 2x16gb kits are now coming as single rank and that might cause a 10-15% performance hit. Not so much on gaming (I'm only a casual gamer and it's mostly RTS at 1440p or 4k so more GPU bound) but on some work stuff where there is quite a bit of data compression/decompression happening. I just don't seem to able to determine what is dual rank and what is a single rank kit any more from a number of "big name" type players. I probably would have bought say Crucial Ballistix 3600 CL16 for £160 last year and moved on. Instead I'm now considering 4x8gb kits or pricier stuff from Gskill etc because there seems a lot more comment about how important dual rank is etc.

@Joxeon: i'm not very familair with 8pack RAM. Is this definately dual rank? It says it's Samsung b-die which I thought usually was but I'm never certain of these things. I did see this OC offer and tried putting the code in this https://benzhaomin.github.io/bdiefinder/ but it didn't seem to recognise it.
 
Reb71 said:
Thanks for the replies. So dual rank matters, topology less so, and the 3600Mhz instability is less of an issue.
On 4. I made a dumb typo. Cleary if they are both 3600 and it's CL18 vs CL16 then the lower Cl16 is better! I meant to say "I don't quite see why 3600MHz CL18 is going to be better than 3200Mhz CL16?" i.e if both have a latency of 10ns, is the 3600 CL18 appreciably better than 3200 CL16?

I'm just concerned that far more 3600 CL16 2x16gb kits are now coming as single rank and that might cause a 10-15% performance hit. Not so much on gaming (I'm only a casual gamer and it's mostly RTS at 1440p or 4k so more GPU bound) but on some work stuff where there is quite a bit of data compression/decompression happening. I just don't seem to able to determine what is dual rank and what is a single rank kit any more from a number of "big name" type players. I probably would have bought say Crucial Ballistix 3600 CL16 for £160 last year and moved on. Instead I'm now considering 4x8gb kits or pricier stuff from Gskill etc because there seems a lot more comment about how important dual rank is etc.

@Joxeon: i'm not very familair with 8pack RAM. Is this definately dual rank? It says it's Samsung b-die which I thought usually was but I'm never certain of these things. I did see this OC offer and tried putting the code in this https://benzhaomin.github.io/bdiefinder/ but it didn't seem to recognise it.
Click to expand...
Yeah all 32gb Samsung b-die kits are dual rank as far as I'm aware.

Capture.png
 
@Joxeon. Appreciate the effort. I strongly suspect it's dual rank since it's seems it's just Team Group Dark Pro with some "8Pack" branding. I'm tempted to get it since it would clearly do the job but it's a bit annoying to pay £208 with delivery for a RAM kit that I will probably never OC to it's full potential.

The alternative though is to take a flyer on some imported Gskill via "the rainforest" or "an egg company" (not sure if I'm allowed to mention competitors on this forum) but returns/RMA could turn into a issue while OC I've found pretty good if anything goes wrong.
 
May sound like a stupid question but how can you tell if ram is single or dual rank? I have Cosair Vengeance Pro RGB but not sure if its single or dual rank and if I would be better upgrading.
 
Steveo1982 said:
May sound like a stupid question but how can you tell if ram is single or dual rank? I have Cosair Vengeance Pro RGB but not sure if its single or dual rank and if I would be better upgrading.
Click to expand...

Install CPUZ and in the spd tab it should show you, ranks dual as you can see in the image below.
Joxeon said:
Yeah all 32gb Samsung b-die kits are dual rank as far as I'm aware.

Capture.png
Click to expand...
 
Joxeon said:
Yeah all 32gb Samsung b-die kits are dual rank as far as I'm aware.
Click to expand...
That's because the largest chip capacity for B-die is 8 Gbit translating to 16 chips needed for 16 GB DIMM.
And with 8 bits wide chip that's half too many bits to fit into 64 bit bus necessitating two ranks.
 
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