should i get 4x8 32gb of ram or 2x16 gb of ram?

[NAMAJAFF]

my motherboard is the ASUS TUF Gaming B550-PLUS and im wondering if i should get another pair of 8gb of ram or just get a pair of 16. ive heard something about not being able to run ram at full speen when all slots are filled.

 

just to be clear: i already have 16gb of ram. and i intend to upgrade to 32 soon-ish and i dont want to make a mistake.

[dizmo]

Either one. Ryzen IIRC has more of a problem with additional RAM sticks than Intel.

[RONOTHAN##]

TL;DR: 2x16GB if you want it to work and not think about it, 4x8GB if you want it to possibly be a little faster.

 

Max speed shouldn't be an issue with this setup, 4x8GB sticks on that board should be able to do 3600MT/s assuming the sticks are the same and can handle it. To be clear, more DIMMs does reduce the speed, but it goes from something like 4800MT/s with 2 sticks (assuming a good board) to 4000MT/s with 4 sticks, both of which are more than the FCLK can handle in synchronized on a Ryzen 3000/5000 series CPU. Your board should be a little worse than that, probably more like 4533 to 3866, but still good enough. The issue with just buying two sticks more sticks though is that unless you're shopping in some very specific speed bins, even if the model numbers on the sticks are the exact same you can still get sticks that won't work with each other. In my experience it's something like 80% they would work just fine, 15% they'll boot but XMP won't enable and/or will crash, and 5% they won't even boot. 

 

The reason I say it will be a little faster though comes down to dual rank vs. single rank. Nowadays it's almost certain that unless you're buying specific speed bins and/or being very specific about what kits you buy, both 8GB and 16GB DIMMs will be single rank. Running 2 single rank DIMMs per channel though will cause the system to effectively run in dual rank mode, and dual rank has a performance uplift similar to 400MT/s extra memory speed at the same timings. On AMD where you do have a max memory speed limited by the FCLK, the extra memory speed afforded by dual rank can be helpful in memory limited workloads. Whether or not it's worth the extra cost and risk of it potentially not working is up to you. 2x16GB DIMMs can be dual rank, especially if you're looking at higher rated ones like 3600 CL14, but for the most part they're all single rank.

[planetary problem]

get a kit of 2x8Gb to add to your current machine, DDR4 has reached the end of its life and any stick of ram you buy now will have zero resale value by the time you are done with them. spending more is stupid for DDR 4. about your stability concerns, you will be fine till 8x4 3200Mhz and probably till 8x4 3600Mhz. don't use memory faster than 3600Mhz (Ryzen infinity fabric issues with speeds higher than that).

 

make sure you are getting the same ram sticks that you currently have or you will be semi dependent on luck. 4 sticks of 3200Mhz will work perfectly fine without any problems if you are running the same sticks of RAM across the 4 slots but at 3600Mhz you might have some problems

[freeagent]

I've been running 4x8 3200C14 for almost 3 years now. Dropping down to two sticks is no good. Boooo. I have 3 Zen 3 parts and all of them have no problem running these sticks.

 

My 5600X can do 1900 1:1 with 4 sticks, and 2000 1:1 with 2 sticks, stable. My 5900X tops out at 1900 1:1 stable with 2 sticks and 4. And my 5800X3D tops out at 1933 1:1 stable with 2 sticks and 4.

 

Edit:

 

Of course I can bench them all much further, but they are WHEA generators.