General Memory Information for Intel® Desktop Boards

Last Reviewed: 24-Jan-2017
Article ID: 000006827

Understanding bits and bytes
A bit is the smallest unit of memory storage and has the value of either 1 or 0 (one or zero). A byte is equal to 8 bits. See the following table for byte conversions.

Size Bytes KB MB GB
1 Kilobyte (KB) 1,024 -- -- --
1 Megabyte (MB) 1,048,576 1,024 -- --
1 Gigabyte (GB) 1,073,741,824 1,048,576 1,024 --
1 Terabyte (TB) 1,099,511,627,776 1,073,741,824 1,048,576 1,024

DIMM (Dual In-line Memory Module) is the term for the memory modules supported by Intel® Desktop Boards. SO-DIMMs (Small Outline DIMMs) are the memory modules for Intel Desktop Boards in the mini-ITX form factor and for laptop computers.


Single- and multichannel memory modes
Several types of memory modes can be configured on Intel Desktop Boards, depending on the number of memory modules installed. The memory mode is either single or one of the multichannel modes (dual, triple, quad, and flex).

  • Single-channel (or asymmetric) mode exists when one DIMM is installed or the memory capacities are unequal.
  • Dual-channel (or interleaved) mode is automatically enabled when the installed memory capacities of multiple DIMMs are equal.
  • All multichannel memory modes increase the transfer speed of data between the DRAM and the memory controller by adding more channels of communication.

See Single- and multichannel memory modes for configuration details.

DDR, DDR2, and DDR3 memory
DDR stands for double data rate and is a type of memory where data is transferred on both the rising and falling edges of the clock signal. DDR2 and DDR3 are updates to the original DDR specification, improving the memory bus speeds.

DDR, DDR2, and DDR3 memory modules are mutually incompatible. You can't install a DDR2 memory module in a board that was designed for DDR3. Voltages, pins, and signaling differ between the memory types.

The key holes on these modules are positioned differently (see image). If you cannot get memory inserted, turn it 180 degrees and try again, or check to make sure you have the correct memory type for your desktop board.

DDR, DDR2, and DDR3

The specification for DDR4 has been released by JEDEC (Joint Electron Devices Engineering Council), an independent engineering trade organization and standards body. DDR4 memory became available in 2014.

Desktop vs. server memory
The memory requirements for desktop computers and servers/workstations are different. Intel Desktop Boards require unbuffered memory. Servers require memory that provides more stability and reliability, and they often use registered or buffered memory. Registered or buffered memory doesn't work in a board that isn't designed for it, and vice versa.

With registered or buffered memory, there is a register between the DRAM modules and the system memory controller. The register stores bits of information so that systems can write to, or read out, all the bits simultaneously. Fully Buffered DIMMs (FB-DIMMs), also used in server environments, include an advanced memory buffer between the memory controller and the memory module.

This article applies to: