Memory Question - Ryzen speed vs capacity

cardsfanbj · January 8, 2022

TL;DR Would you rather have 32 GB at slower speed or 16 GB at 3200MHz

Relevant Specs:

Ryzen 7 2700X

Asrock X470 Gaming K4

G.Skill Trident Z RGB 2/4 x 8 GB 3200 MHz CL16 (16-18-18-38)

My PC as it sits has 2x8GB G.Skill Trident Z RGB. Wanted to upgrade to 32 GB for Chrome reasons. Went on sale for Black Friday for $65.69 and my mom put it away for me for Christmas, so I didn't get around to installing them until after Christmas, but Newegg's return policy allows for returns through January 31st for items bought from Newegg and not 3rd party sellers.

For Christmas this year, I got a matching kit to bump it up to 32 GB, but when I booted it up it started blue screening as soon as I loaded into Windows. Cleared CMOS to clear the XMP settings and it boots fine at stock speed. Reenabled XMP (ASRock UEFI specifically refers to it as XMP settings) and BSOD returned. Posted to a facebook group and some people said the issue could be mismatched DRAM chips, but as far as I can tell they're all Samsung B-dies.

Looked closer at the motherboard manual and the max it "officially" supports is 2667 single channel or 2133 dual channel in four slots. I've successfully run dual channel (slots A2/B2) at 3200 MHz so by that logic I would guess I could maybe run memory in 4 slots at 2667. I haven't tried messing with it in a week, but maybe hopefully I could get it to get it to run at 3000 MHz, but I recognize that might not work.

I've also gotten some recommendations to try overvolting the memory, but I've never messed with manually overclocking RAM, just clicking the XMP profile.

Jurrunio · January 8, 2022

SR and DR refer to single rank and dual rank, basically memory dies on one side or two sides. Not channel.

The problem is 16GB rated at 3200 doesnt mean they are rated for 32GB at 3200. You need better sticks to actually achieve that. 4x8GB kits do not cost more just by being more premium as some might think

4x8 is still preferred, performance might get better even. Take some games and benchmark those

mariushm · January 8, 2022

On that motherboard, you can probably run 4 sticks at 2933 / 3000 Mhz. If you're lucky, may be able to do 3200 Mhz.

Two sticks will run at 3200 or 3600 Mhz.

Four sticks puts a bit more stress on the motherboard so it's possible you could run 2 sticks at 3200 Mhz, but could not run 4 sticks at 3000 Mhz.

Those frequencies listed are the ones the processor "officially" supports, just like Intel officially supports maximum 2666 Mhz or 2933 ( for example see here Intel i7 10700k officially supports maximum 2933 Mhz, but you can use 3600 Mhz or higher sticks just fine if the motherboard is well built : https://ark.intel.com/content/www/us/en/ark/products/199335/intel-core-i710700k-processor-16m-cache-up-to-5-10-ghz.html )

Ryzen processors work best with ram sticks up to 3600 Mhz.

Ryzen 2nd generation is a bit more sensitive about high frequencies ... depends on motherboard and cpu, some combinations work fine with 3600 Mhz sticks, some are a bit picky and it's better to stay with 3200 Mhz.

Basically, think of it like ... if 3600 Mhz is 100% performance possible, 3200 Mhz is maybe 98.5% performance, 3000 Mhz is maybe 95% performance and 2666 Mhz is maybe 87-90% performance.

A lot of people went with 3200 Mhz because simply the price difference between 3600 and 3200 Mhz was too big to be worth it.

You could use CPU-Z or Aida64 to note down the SPD profiles and pick one that's between 2666 Mhz and 3200 Mhz and then go in BIOS and manually set the frequency and timings.

For example, my Corsair sticks only have 3200 Mhz 16-20-20-38 profile, and the default JEDEC 2133 Mhz and lower profiles, but I could basically use the timings of the XMP-3200 profile with any lower frequency while keeping that 1.35v voltage without any worries. The 1.35v is required to achieve 3200 Mhz at those timings.

PS. Dual Rank doesn't mean ram chips on both sides of the ram sticks as @Jurrunio says, but it just so happens that majority of manufacturers make dual rank sticks by placing chips on both sides, as it makes routing the traces to the pins on the stick easier.

Majority of 8 GB sticks are Single Rank these days, because ram manufacturers no longer make 4 Gbit chips, they focus their production on 8 Gbit and 16 Gbit chips. For a dual rank 8 GB stick, ou'd need 16 chips, 8 on each side of the stick, and you'd need 512 MB (4 Gbit) chips ... so 16 chips x 4 Gbit = 64 Gbit / 8 = 8 GB stick )

Dual Rank means that the memory on a stick is arranged in two virtual "buckets" of memory. The memory controller on the CPU can give a command to one rank to retrieve data from a particular location in that rank, and give a different command to the other rank, so while a rank is busy with something the cpu can work with the other rank and not waste time waiting for stuff.

So Dual Rank memory sticks can give an additional performance bump (but very small, and not in all applications) over single rank sticks.

Single Rank sticks are preferred by overclockers because it's less "stress" on the motherboard and the memory controller in the CPU making it possible to achieve higher frequencies without making the memory sticks "unstable" - it's less risk of getting memory errors.