ASRock C2550 & ECC Memory Expansion by 8GB stick possible with current 4GB stick

[danioj]

Firstly, I know there are numerous threads out there containing the use of the ASRock C2550 BUT they are all build threads and I didn't want to hijack!

 

Well, as that above sentence (and the subject) might imply, I have this board. It is currently installed in my Backup Server.

 

I feel I made a mistake when I built this machine. At the time I decided it was going to do nothing else but sit there and backup my Main Server (which has all my power and grunt) and then go to sleep. I have now decided however to install pfsense on it. Thats fine in the most part. Nice speedy cpu, sad for installation ..... WAIT .... only 4GB of RAM in the box!  Doh!

 

Not ONLY did I put 1 stick of RAM in the box I put 1 SODIMM of 4GB RAM instead of an 8GB. Sigh. I feel I "might" now (at some point in the future) extend what this box does and need to add more RAM BUT I don't want to loose my 4GB Stick until I don't have to.

 

So, to my question ....

 

Can I Safely put an 8GB Stock of this ECC Memory into the server making the total 12GB without issue - until I EVENTUALLY add 8GB sticks to each of the 4 slots and then sell the 4GB stick?

 

I remember back in the day Memory was always to be installed in pairs and then by channel. I have always followed this rule without even knowing it so I have never had an issue. Is this still the case today?

[garycase]

There's no problem installing an 8GB module.    The only thing that will do is cause the memory to run in a degraded dual channel mode.  But since you're currently running in single channel mode, that's actually a bit of an improvement anyway.  ... when you eventually replace the 4GB module with another 8GB module the memory will run in the optimal synchronous dual channel mode.

 

[danioj]

There's no problem installing an 8GB module.    The only thing that will do is cause the memory to run in a degraded dual channel mode.  But since you're currently running in single channel mode, that's actually a bit of an improvement anyway.  ... when you eventually replace the 4GB module with another 8GB module the memory will run in the optimal synchronous dual channel mode.

 

Thanks for the quick reply buddy!

 

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[HellDiverUK]

Most recent Intel chips have "Flex Memory" which allows different sized DIMMs to run in dual channel.

[garycase]

Most recent Intel chips have "Flex Memory" which allows different sized DIMMs to run in dual channel.

 

That's been true for several years -- although the dual channel mode with mixed sizes isn't the optimal sync dual channel mode that will be used with matching size modules.  However -- since in this case the configuration currently only had one module (and was thus running in single channel mode), it's still an improvement in memory transfer speed in addition to tripling the amount of memory