The board has two DIMM sockets and supports the following memory features: • Two independent memory channels with interleaved mode support • Supports 1.5 V DIMM memory voltage • Support for non-ECC, unbuffered, single-sided or double-sided DIMMs with x8 organization • 16 GB maximum total system memory (with 4 Gb memory technology). Refer to Section 2.1.1 on page 35 for information on the total amount of addressable memory. • Minimum total system memory: 1 GB using 1 Gb x8 module • Serial Presence Detect • DDR3 1333 MHz and DDR3 1066 MHz SDRAM DIMMs...
If you currently have 2x1GB, you will need to buy two larger modules and replace it (as opposed to add to it). You can use a memory selector to help with RAM choices, such as Crucial - http://uk.crucial.com/gbr/en/compatible-upgrade-for/Intel/dh61ho (or the site more suited to your own currency)
However, if you have a single stick of 2GB in there, and just want to double the RAM, go looking for another Hynet 2GB 1333 stick to get 4GB.
The board has two DIMM sockets and supports the following memory features: • Two independent memory channels with interleaved mode support • Supports 1.5 V DIMM memory voltage • Support for non-ECC, unbuffered, single-sided or double-sided DIMMs with x8 organization • 16 GB maximum total system memory (with 4 Gb memory technology). Refer to Section 2.1.1 on page 35 for information on the total amount of addressable memory. • Minimum total system memory: 1 GB using 1 Gb x8 module • Serial Presence Detect • DDR3 1333 MHz and DDR3 1066 MHz SDRAM DIMMs