[SOLVED] Will RAM configuration of 16gb + 8gb work in dual channel?

[PRusov]

Once again in my time of need, I turn to Tom's Hardware!

Hey guys, I have a question. I bought my PC about a year and half ago and at the time, since I didn't know any better, I got 16gb single channel RAM (HyperX 3200MHz module). Now, I've found out that dual channel works a lot better in basically every game/CPU intensive task. So, if I get a 8gb module, same make/latency/speed as my 16gb one (basically the same thing only smaller, because I don't need 32gigs), making it a combined 24gb RAM size, will it act in said dual channel mode? I know it seems stupid, but for dual channel to be utilized to it's fullest, do the modules need to be the same size? In other words, will I see improvement in 16+8 config over the 16? And yes, I am aware that a small percentage of applications can utilize it all, but I'm more concerned with speed, rather than space.

My motherboard is an Asus TUF B450-Plus Gaming
...prolly should've read the manual huh?

Thanks in advance boys.

 

[Dakshthenoob]

How much mhz are u running
When u run at the same 2666 or 3200 mhz means it will run fine

 

[JohnBonhamsGhost]

mixing RAM kits is never recommended.
even if they boot and your OS loads you may be facing other issues with decreased performance, increased latency, random crashing due to data corruption, etc.
and I would be surprised if dual-channel optimizations even showed using different kits.

if for some reason you really need >16GB you should purchase a 32GB kit that is in the motherboard QVL.

 

[InvalidError]

Modern CPUs can run memory in mixed mode where access will be interleaved between the two channels up to the capacity of the lowest memory channel and single-channel afterwards. This may cause some jittery performance issues due to different memory address ranges having different bandwidth and latency.

Memory is only guaranteed to work together when added as a kit, so your mileage may vary if you add any random combination. Depending on your luck, it may work out-of-the-box, it may require manual tweaking or could possibly turn into a no-go and force you to go down the replacement route anyway.

I haven't run into issues mixing DIMMs myself but there are no guarantees.

 

[PRusov]

How much mhz are u running
When u run at the same 2666 or 3200 mhz means it will run fine

In my current setup, I'm running a single stick 16gb RAM at 3000MHz (Even though the model is marketed at 3200MHz, I never managed to make it work at said frequency). The other stick I'm planning to buy is also labeled as "3200MHz", however I'd use it in 3000MHz config.

 

[PRusov]

mixing RAM kits is never recommended.
even if they boot and your OS loads you may be facing other issues with decreased performance, increased latency, random crashing due to data corruption, etc.
and I would be surprised if dual-channel optimizations even showed using different kits.

if for some reason you really need >16GB you should purchase a 32GB kit that is in the motherboard QVL.

I understand that, and like I said, I don't need 32gb of RAM, however I'd like to have it run in dual channel, so, I'm wondering if that can be achieved with a mismatch of RAM sizes. Nothing more. Because it would be a hassle to sell my current stick and buy 2x8, if I can have the same performance improvement with a 16+8 configuration. And the sticks would be basically identical, with the only discernable difference being the size of the stick.

 

[PRusov]

Modern CPUs can run memory in mixed mode where access will be interleaved between the two channels up to the capacity of the lowest memory channel and single-channel afterwards. This may cause some jittery performance issues due to different memory address ranges having different bandwidth and latency.

Memory is only guaranteed to work together when added as a kit, so your mileage may vary if you add any random combination. Depending on your luck, it may work out-of-the-box, it may require manual tweaking or could possibly turn into a no-go and force you to go down the replacement route anyway.

I haven't run into issues mixing DIMMs myself but there are no guarantees.

Thanks for the reply! It was some really cool and useful info. I have an AMD Ryzen 5 3600. Do you know anything about the compatibility of RAM size miss-matches with that particular cpu? I got a reply on reddit saying that I'd be okay for any game/task that uses <16 gb of RAM total because I'd run like a 2x8 ram kit in dual channel, with the remaining 8gb running in single channel when it's needed (which would be rarely, if ever). Do you think that's correct?

 

[Bob.B]

I understand that, and like I said, I don't need 32gb of RAM, however I'd like to have it run in dual channel, so, I'm wondering if that can be achieved with a mismatch of RAM sizes. Nothing more. Because it would be a hassle to sell my current stick and buy 2x8, if I can have the same performance improvement with a 16+8 configuration. And the sticks would be basically identical, with the only discernable difference being the size of the stick.

In theory you will have 16GB running dual channel and 8GB running single channel.
Make sure you plug the sticks into the proper slots......see the manual.

 

[InvalidError]

I got a reply on reddit saying that I'd be okay for any game/task that uses <16 gb of RAM total because I'd run like a 2x8 ram kit in dual channel, with the remaining 8gb running in single channel when it's needed (which would be rarely, if ever). Do you think that's correct?

Modern OSes randomize the memory space so malware has a harder time finding the address of target code and data. Applications have little or no control over what part of physical memory space their memory allocations will come from. Chances are your games and application will get a mix of single and dual channel memory allocations.

 

[JohnBonhamsGhost]

I don't need 32gb of RAM, however I'd like to have it run in dual channel, so, I'm wondering if that can be achieved with a mismatch of RAM sizes.

as has been stated multiple times in this thread alone;
you may get some sort of dual-channel support, but you may also be experiencing many other negative aspects of trying to mix these different kits.
this will often lead to instability or noticeable lack of performance, even at random times.

Because it would be a hassle to sell my current stick and buy 2x8

it's more of a hassle posting an ad for sale
than possibly spending hours troubleshooting and diagnosing future issues that could arise from attempting this?
or having reduced performance in a system that you are trying to actually get more performance out of?