1 8gb DDR4 + 2 4gb DDR4 = 16gb

[ANXsucks]

Is it fine to use one stick of 8gb DDR4 ram and pairing it with 2 4gb sticks to have a total of 16gb of ram? I'm planning on building a PC and my budget would only support 12gb of RAM which I think is fine. Then in the future I want to buy another 4gb stick to have a total 16gb, but would I face compatibility issues or bad RAM speeds?

 

[Guest]

Yes, but is it the same speed? It will work, but be less than optimal. If not the same speed, they will find the lowest common speed and function at that level. Also, one will work on double-channel, the other one single-channel. So it will be very inefficient, but it will act as 12 GB of RAM.

But then you want to do 3*4GB + 8GB = 16 GB? Nope, that won't work.

You will have bad RAM speeds regardless. All RAM sticks should be the same size and same frequency and timing to ensure good function.

 

[VJ_Gamer]

Which is your motherboard? Few of the motherboard supports dual channel and few of them supports quad channel. So if your motherboard supports dual channel its better to stick with two ram sticks instead of three. And try to match your ram sticks speed, timings etc to avoid compatibility issues.
Even the same model or make would be better.

Peace.

 

[Sakkura]

When you mix RAM there's always some risk of compatibility issues. But in principle, 2x4GB + 1x8GB will work perfectly fine as a 16GB dual channel configuration. Both the 4GB sticks in one channel will be matched with the single 8GB stick in the other channel for dual channel operation.

 

[ANXsucks]

They're probably 2133mhz. The motherboard I'm hoping to use is the Asrock B250m pro4 which will be paired with the Pentium G4560.

 

[VJ_Gamer]

Your motherboard supports dual channel, So if you add two 4gb sticks to the dual channel, the 4gb sticks will run in dual channel and one with 8gb will run in single channel. If your motherboard supports flex mode then there wont be and issues as the two channels(dual and single) will be running 8gb ram on it. But if it doesn't support flex mode then there might be a negligible performance drop which you will hardly notice.

Good Luck. Peace.

 

[Sakkura]

Your motherboard supports dual channel, So if you add two 4gb sticks to the dual channel, the 4gb sticks will run in dual channel and one with 8gb will run in single channel. If your motherboard supports flex mode then there wont be and issues as the two channels(dual and single) will be running 8gb ram on it. But if it doesn't support flex mode then there might be a negligible performance drop which you will hardly notice.

Good Luck. Peace.

This is not correct. With two 4GB sticks and an 8GB stick, it will all run in dual channel if set up correctly. See the "Dual-channel with three DIMMs" example here:

https://www.intel.ca/content/www/ca/en/support/boards-and-kits/000005657.html

(the example has 2x2GB + 1x4GB instead of 2x4GB + 1x8GB, but the principle is the same)

 

[VJ_Gamer]

Your motherboard supports dual channel, So if you add two 4gb sticks to the dual channel, the 4gb sticks will run in dual channel and one with 8gb will run in single channel. If your motherboard supports flex mode then there wont be and issues as the two channels(dual and single) will be running 8gb ram on it. But if it doesn't support flex mode then there might be a negligible performance drop which you will hardly notice.

Good Luck. Peace.

This is not correct. With two 4GB sticks and an 8GB stick, it will all run in dual channel if set up correctly. See the "Dual-channel with three DIMMs" example here:

https://www.intel.ca/content/www/ca/en/support/boards-and-kits/000005657.html

(the example has 2x2GB + 1x4GB instead of 2x4GB + 1x8GB, but the principle is the same)

Check the link description.
Rules to enable dual-channel mode
To achieve dual-channel mode, the following conditions must be met:
Same memory size. Examples: 1 GB, 2 GB, 4 GB.
Matched DIMM configuration in each channel.
Matched in symmetrical memory slots.

Configurations that do not match the above conditions revert to single-channel mode

So if you add two 4gb in the dual channel, it will run in dual channel. But the third 8gb stick will run as a single channel.

Peace.

 

[Sakkura]

Check the link description.
Rules to enable dual-channel mode
To achieve dual-channel mode, the following conditions must be met:
Same memory size. Examples: 1 GB, 2 GB, 4 GB.
Matched DIMM configuration in each channel.
Matched in symmetrical memory slots.

Configurations that do not match the above conditions revert to single-channel mode

So if you add two 4gb in the dual channel, it will run in dual channel. But the third 8gb stick will run as a single channel.

Peace.

Again, that's not correct. You're misreading the requirements. Look at the pictures, it clearly shows 2x2GB plus 1x4GB can run in dual channel.

What you're describing sounds like flex mode, which is illustrated at the bottom of the page. That only kicks in when more memory is installed in one channel than the other, which wouldn't be the case with OP's configuration of 2x4GB + 1x8GB, as the single 8GB stick would match up with the combined 8GB of the two 4GB sticks.

 

[VJ_Gamer]

Again, that's not correct. You're misreading the requirements. Look at the pictures, it clearly shows 2x2GB plus 1x4GB can run in dual channel.

What you're describing sounds like flex mode, which is illustrated at the bottom of the page. That only kicks in when more memory is installed in one channel than the other, which wouldn't be the case with OP's configuration of 2x4GB + 1x8GB, as the single 8GB stick would match up with the combined 8GB of the two 4GB sticks.

It is showing how to maximize the performance and optimize the dual channel mode if you have two sticks of ram of the one size and one of different size. As per the figure if you place one 4gb and 2gb in the same color code and one more 2gb on the other color code then the dual channel wont be optimized because you are placing 4gb with the 2gb to work together with dual and hence all the sticks will work on the single channel. So if you add 2 of the same size ram on the same color code them you will optimize the dual channel for those two sticks.

Peace.