What is the Largest Size of DDR3 RAM Modules for Your Motherboard?

The amount of RAM you can install on a motherboard with two DDR3 slots depends on the specific motherboard model and its specifications. Typically, DDR3 RAM modules come in sizes up to 16 GB per module. Therefore, if your motherboard supports this capacity, the maximum amount of RAM you could install would be:

2 slots x 16 GB per slot 32 GB total.

Understanding DDR3 RAM

The DDR3 standard permits DRAM chip capacities of up to 8 gibibits (GiB) and up to four ranks of 64 bits each for a total maximum of 16 gibibytes (GiB) per DDR3 DIMM. This means that while a single module can be up to 16 GB, not all motherboards will support this maximum capacity.

Checking Your Motherboard for Compatibility

The only way to know the specific limits of your motherboard is to visit the manufacturer's data page for the board and look at the “Approved Vendors” list for RAM compatibility. While you don't have to buy the exact brands and models listed, it's a good indication of what the motherboard can support. If you only see 8 GB modules on the list, it is unlikely that 16 GB modules will work. However, there is a chance that 16 GB modules may work, so it's up to you to decide whether to take the risk.

Boards will vary from one manufacturer to the next, and the maximum individual module size, frequency, and type the board supports can vary significantly. Therefore, you’ll need to look up your computer model or motherboard model and then look up the specifications on the board from the manufacturer. There isn't a one-size-fits-all answer to this question.

Checking Specific Specifications for Your Motherboard

According to specifications, the maximum capacity per module of a single DDR3 module is 16 GB. However, not all DDR3-capable motherboards will handle this capacity. When building my latest machines, I checked with AMD first because the manual only recommended 8 GB modules. The answer was that the particular board had never been tested with 16 GB modules at that time and that while there would be no damage, performance uncertainty remained. Since I am not a gambler, I fully populated the boards with four 8 GB sticks, totaling eight sticks across two machines. The vendor queried why I was buying ten sticks, and my answer highlighted the flexibility and expectations:

If you don’t have the manual for your motherboard, you can find the precise specs by searching online using the brand and model number. Some boards may potentially support higher capacities, but it’s best not to make assumptions without verification.

While you can use higher-speed modules beyond what your motherboard specifies, doing so will not provide any better performance. The motherboard will not recognize or utilize the higher speeds, so you might as well stick with the recommended specifications for the best compatibility and performance.