can i add 1x8gb of ram with my 2x4gb of ram?

[CatsAreAwesome26]

upgrading some of my pc parts and atm only got 2x4gb(8) of ram and wanted to bring it up to 16 will it be ok if i add 1x8gb stick of ram to my pc? my motherboard is the "MSI B350 PC MATE" im open to suggestions :)

[ElClapo]

Originally posted by RanchConsumer:

upgrading some of my pc parts and atm only got 2x4gb(8) of ram and wanted to bring it up to 16 will it be ok if i add 1x8gb stick of ram to my pc? my motherboard is the "MSI B350 PC MATE" im open to suggestions :)

yes but if there not all the same speed your pc will run at the slowest ram speed

[_I_]

not all mobos support mixing single and dual ch at the same time
most will be back to single ch, and if it did, the 8g dimm would be in single mode anyway

best to get a similar 2x8g kit or matchng 2x4g kit

[𝔇ave]

of course you can but in order for all your memory capacity to run at optimal speed it would be best to match capacities and speeds across all populated DIMM slots. since Ryzen is especially influenced by memory configuration i would think that to be more important than on an equivalent Intel based system

[hawkeye]

The mobo manual will say what happens. It's possible that the 8gb will be treated as another 4. Get a 2 x 8 kit or another 2x4 if the mobo has the slots.

[_I_]

mobos will not reduce the amount of ram when mixing dual+single ch
you can put in whatever you want, it may not run at each dimms max speed or best timigs

many will allow dual ch for 2 different sized dimms
(2x lowest capacity will be dual ch while the remaining will be single ch)
ex 2g+8g in dual ch = 4g in dual ch + 6g in single ch speeds

[faking chater]

Better of all is adding the same 4gb ram to your pc. Buying two 4gb gotta be better then buying one 8gb.

[Overseer]

I've actually never seen or heared of tests with only 3 DIMMs on Ryzen. Generally i would say it should work with a modern board but the performance could be all over the place. And things get even more complicated with the different memory layouts on boards.
Considering this is Steam and you probably want to game with it, i would advise against 3 DIMMs.

[tacoshy]

Originally posted by _I_:

not all mobos support mixing single and dual ch at the same time
most will be back to single ch, and if it did, the 8g dimm would be in single mode anyway

best to get a similar 2x8g kit or matchng 2x4g kit

Of course all do. It not mixing single and dual channel in the first place. Put 2x4GB in channel A and the 1x8GB in channel B and you're done.

Also motherboard does not need to support it. It's a CPU thing.

Originally posted by _I_:

mobos will not reduce the amount of ram when mixing dual+single ch
you can put in whatever you want, it may not run at each dimms max speed or best timigs

many will allow dual ch for 2 different sized dimms
(2x lowest capacity will be dual ch while the remaining will be single ch)
ex 2g+8g in dual ch = 4g in dual ch + 6g in single ch speeds

It's called Flexmode and its again not a Motherboard but a CPU thing (IMC). Every CPU the last 10-15 years support it.

Originally posted by Overseer:

I've actually never seen or heared of tests with only 3 DIMMs on Ryzen. Generally i would say it should work with a modern board but the performance could be all over the place. And things get even more complicated with the different memory layouts on boards.
Considering this is Steam and you probably want to game with it, i would advise against 3 DIMMs.

Depends on the setup. Dual channel does not mean to use identical modules nor an even ammount of modules. The only thing that needs to be done for 100% dual channel (not flexmode) ist that both channels ahve the same capacity. If you put 2x4GB in Channel A and the 1x8GB in Channel B, both channels have the same capacity and dual channel will work correctly all the time.

https://steamcommunity.com/groups/Master_Race_Geeks/discussions/0/2747650363459040918/

[vadim]

Tacoshy is right as usual. I can confirm what he said.

[nullable]

Also mention, as far as games are concerned, there's often very little performance benefit to dual channel. I mean sure, run full dual channel if you can (I always do), flexmode is fine too. Single channel is not the end of the world though, dual channel doesn't come anywhere near to doubling performance in most uses cases. And the reality is 16GB in single channel or flex mode > 8GB in dual channel, especially any time you need more than 8GB of RAM.

But don't take my word for it, look it up. This is a perpetual discussion point and there's always a few fairly recent articles bench-marking the performance of dual channel vs single channel to counter-weight all the FUD of people pushing dual channel as an absolute necessity.

[Overseer]

Originally posted by Brockenstein:

But don't take my word for it, look it up. This is a perpetual discussion point and there's always a few fairly recent articles bench-marking the performance of dual channel vs single channel to counter-weight all the FUD of people pushing dual channel as an absolute necessity.

Please specify "absolute necessity".
I remember a bench from GamersNexus from like a year ago with Ryzen and their numbers showed a difference of up to 80% in framerate. 80% is certainly not double but far from insignificant.

Originally posted by tacoshy:

Depends on the setup. Dual channel does not mean to use identical modules nor an even ammount of modules. The only thing that needs to be done for 100% dual channel (not flexmode) ist that both channels ahve the same capacity. If you put 2x4GB in Channel A and the 1x8GB in Channel B, both channels have the same capacity and dual channel will work correctly all the time.

While this sounds all logical, it does not say anything about Ryzen performance on 3 DIMMs. Given the fact that Ryzen already struggles with 4 identical DIMMs on Daisy Chain i would assume 3 of different kind will go real hard on the memory controller. Which makes me wonder what frequencies can be achieved, in which slots those 3 DIMMs should go and what the performance difference on T-Topology compared to Daisy Chain is.

[nullable]

Originally posted by Overseer:

Please specify "absolute necessity".

"Oh my god, your PC basically won't work unless you do this"

Originally posted by Overseer:

Please specify "absolute necessity".
I remember a bench from GamersNexus from like a year ago with Ryzen and their numbers showed a difference of up to 80% in framerate. 80% is certainly not double but far from insignificant.

Well let me know if you find that crazy article, I couldn't.

https://hardforum.com/threads/ryzen-2-single-channel-vs-dual-channel-best-ram-settings.1967859/ I did find this, and yeah there's of a performance penalty depending on the game. Ryzen is a bit sensitive to RAM speed and timings. In a lot of cases unless you have the optimal RAM configuration though you take as much of a performance hit from just running dual channel without tweaking as you do running single channel instead of dual channel.

And regardless if you need more than 8GB of RAM 16GB in single channel is going to be better. But ideally you would run dual channel if you could.

And I will admit my first post was thinking too much about Intel's more forgiving performance with RAM as opposed to Ryzen's dependence on optimal configurations.