Rack servers come with extensive slots for RAM Modules – significantly more so than devices such as laptops and desktops).  That makes sense since rack servers are designed to be enterprise-grade equipment that is customizable and upgradeable. 

Can you upgrade the RAM on a server?  The short answer is most definitely yes, and you can even mix RAM of different capacities and speeds in the same machine.  But there are a couple of caveats to keep track of, and we’ll walk you through them. 

First, Let’s Cover the Basics of Server RAM 

Server memory has several features that make it unique and different from RAM that you would find in conventional desktops. 

• ECC (Error Correction Code) – ECC RAM is a type of RAM that has an additional chip for limiting data corruption. While technically, there are situations where you may be able to use non-ECC RAM in a server, if the server’s system specs state that it takes ECC RAM, it’s best to stick with it. 

• Registered RAM – Registered RAM (sometimes referred to as ‘Buffered’) has an additional circuit on the Module to place less electrical load on the memory controller.

Almost certainly, your server RAM has the above features in its existing memory modules.  However, you should always check the system specs to confirm what RAM your server takes. 

WE HAVE TONS OF RESOURCES ON RAM!  You can read our general RAM Compatibility primer here.  Are you wondering how much RAM you need?  We have a post on that as well!

RAM Upgrade Do’s And Don’ts 

• You CAN mix RAM of different capacities on the same server – but the order you install the RAM will matter (more on that later). In other words, you can have 8GB and 4GB modules mixed in a server, but you will want to have the higher capacity modules split evenly between the two processors (assuming the server is a two-socket system).
• You CAN mix LV (Low Voltage) RAM and non-LV RAM, but RAM will automatically run at the higher voltage.
• You CAN combine different speed RAM modules – but then all the RAM will then default to the lower speed module.

Under the Hood 

Assuming you have compatible RAM, let’s look at the actual installation order in the server.  The diagram below is illustrated with a Dell R620, but the principles would be the same for virtually all servers.

A WORD ON “RANKINGS.” Memory Rank refers to how many data blocks are on a memory module.  You can have Single Rank, Dual Rank, or Quad Rank.  If you intend to max out the RAM on your server, you will need to confirm that all modules are the same rank. 

Final Thoughts 

If you are new to upgrading RAM, the compatibility pitfalls and installation can seem daunting at first.  But if you follow the principles, it can be a straightforward process. 

And don’t forget – we have techs and reps on standby to answer all of your RAM upgrade questions!