Question Will it cause problems if a pair 1R x 4 mixing with a pair of 2R x 4 ?

[Wing901]

And both pairs are different in size.

 

[Ralston18]

Very likely yes.

RAM should be selected and installed in accordance with the motherboard's manufacturer's User Guide/Manual with verification via the manufacturer's website.

RAM must be installed in matched sets and will likely need to be installed in some specific physical order. Usually starting with DIMM_A2.

There are often BIOS related configurations that need to be correcly set.

3 possible outcomes if something is not as it should be: 1) seems to be working, 2) works with continual problems, and 3) does not work at all.

Mixing and matching RAM is not recommeded.

 

[Wing901]

Thanks.
Sometimes, user manuals make me confused. For example, the specification says the motherboard can be installed up to 512G ECC RDIMM(total 8 slots), but the menu indicates, "If you are using a RDIMM memory, make sure it is a 1Rx8 one." I could not find any DDR4 1Rx8 64G RAM stick in the market. I wonder if it is ever existed. Most likely 8G is maximum.

 

[geofelt]

If you have them, try them.
The ram will operate at a lower common spec, if at all.
You may need to increase the ram voltage in the bios and lower the speed to get things to work.
Then, run a couple of full passes with memtest with NO errors to confirm proper functioning.

Now, all that said, mismatched ram is likely to have problems.
Better to get a supported matched kit.

 

[Wing901]

Both pairs of RAM are in the same speed and both are ECC RDIMM, but their size/capacity are different, and also one pair is 1R x 4, and the other pair is 2R x 4.

How do I check if they can work together? Is there any software to do it?

 

[JeffreyP55]

Both pairs of RAM are in the same speed and both are ECC RDIMM, but their size/capacity are different, and also one pair is 1R x 4, and the other pair is 2R x 4.

How do I check if they can work together? Is there any software to do it?

Bin matching is important. Mixing & maxing may give you bad gas.

 

[Eximo]

How do I check if they can work together? Is there any software to do it?

Plug them in.

As others mentioned there should be a table of memory population rules in the the motherboard manual.

But generically, you are trying to create memory banks. So you would pair the dissimilar memory together, with another pair of the same dissimilar memory in another channel.

1x4 + 1x8 in channel A, 1x4 + 1x8 in channel B

For a quad channel, you could try 1x4 1x8 1x4 1x8 and hope that the system will use the first 4GB of each stick (or whatever the capacity is) in quad channel.

 

[Wing901]

Plug them in.

As others mentioned there should be a table of memory population rules in the the motherboard manual.

But generically, you are trying to create memory banks. So you would pair the dissimilar memory together, with another pair of the same dissimilar memory in another channel.

1x4 + 1x8 in channel A, 1x4 + 1x8 in channel B

For a quad channel, you could try 1x4 1x8 1x4 1x8 and hope that the system will use the first 4GB of each stick (or whatever the capacity is) in quad channel.

I just tried to see if it works or not. The system can boot up and run some programs. But what will happen if memory consuming programs are running at the same time is yet to see.

 

[geofelt]

Run
memtest86.

It does not use windows.

If it runs a full test with NO errors, you are likely OK.

To be sure, run a couple more times.

 

[beyondlogic]

And both pairs are different in size.

Yea your more likely to run into conflicts mixing ram is never advised it's why there bought in kits and you shouldn't run a single rank and a duel rank either.

It may not access all of the duel rank memory.

The system might try to flex everything into single rank or run the duel rank in duel channel when accessed most likely cause a crash when fully loaded.