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1Rx8 vs 1Rx16

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Zerileous

Senior Member
Joined
Jun 21, 2002
Here is another (mostly) Ryzen strange memory performance quirk. We all saw the dual rank (or 2x single rank via 4 sticks) vs single rank (https://hardwarecanucks.com/memory/choosing-the-best-amd-ryzen-5000-memory-a-beginners-guide/#ranks). Now a Linus video is reporting up to 10% performance difference on laptops with 1Rx8 vs 1Rx16 (half as many chips in the latter) in some games.
. I wonder if this is reproducible and I wonder if this is related to the single/dual rank issue.

edit: I accidentally included an article addressing single vs dual channel instead of single vs dual rank.
 

bmwbaxter

Joined
Jun 9, 2010
It wasn't just limited to the AMD system, the Intel system saw a comparable performance hit when paired with the "slow" ram.
 

Woomack

Benching Team Leader
Joined
Jan 2, 2005
It's more like things you can't see. Less chips = higher density IC (generally every IC is going this way). Higher density = more relaxed sub timings and also configurable ones in the SPD. Here you have these couple of % performance. I wouldn't blame it on 1Rx8 vs 1Rx16 but simply totally different memory profiles. SPD has maybe 12 timings, this is programmable. Everything else is automatically adjusted by BIOS when it's recognizing/training the memory module. So 1Rx8 in this case is single rank and additionally is trained like 32GB modules. Think about DDR4-3200 with tRFC at about 800.
Other way, less chips = cheaper production and can use the same IC in 8GB, 16GB and 32GB modules. So 4, 8 and 16 chips on a single memory module.

As long as 1Rx8 is a "starter" memory and laptops come with 1 module, then it's like instant replacement for most users. The only problem is when laptop has only one socket or RAM is soldered.

It's the same with SSD. Brands like Lenovo or Dell are selling cheaper and business series laptops with short, DRAM-less M.2 SSD that are cheaper but lack performance.
 

bmwbaxter

Joined
Jun 9, 2010
Does that mean that the “fast” ram set to the “slow” ram timings would perform the same?


 

Woomack

Benching Team Leader
Joined
Jan 2, 2005
Does that mean that the “fast” ram set to the “slow” ram timings would perform the same?

Yes and no ... at least in the case of SODIMM. Yes as you can adjust SPD but there are only ~12 timings (as long as you can edit the SPD). No, as you can't adjust additional timings and the motherboard will always set very relaxed sub-timings on the "slow" RAM.
The typical user can't make anything with that if it's SODIMM as to edit/adjust SPD/timings is required:
1. Laptop with XMP support or memory settings in BIOS. Most laptops don't have that.
2. Software like Thaiphoon Burner - not all memory modules are unlocked for programming so software may not work.
3. Hardware programmer - like anyone will get that for a single memory kit.

I made some SODIMM reviews with SPD editing but most were covering 2x32GB kits so dual-rank + dual-channel and high JEDEC profiles.

If there is a standard DIMM in use then you can adjust most timings manually on better motherboards.

@ed, he actually said the same as I did but on different examples :) I see he didn't like Linus video and made his own ... also some viewers made stupid comments to his comment so I guess he wanted to prove something ;)