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.
|1 Kilobyte (KB)
|1 Megabyte (MB)
|1 Gigabyte (GB)
|1 Terabyte (TB)
DIMMS and SO-DIMMS
Dual In-line Memory Module (DIMM) 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 multi-channel 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 multi-channel 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 multi-channel memory modes increase the transfer speed of data between the DRAM and the memory controller by adding more channels of communication
See Single- and multi-channel 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 cannot 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.
The specification for DDR4 has been released by JEDEC (Joint Electron Devices Engineering Council), an independent engineering trade organization and standards body. DDR4 memory is expected to be 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 often use registered or buffered memory. Registered or buffered memory does not work in a board that is not 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 applies to: