Multi-Channel, ECC, and Virtual Memory

(OBJ 3.3)

Multi-Channel Memory

Multi-Channel Memory - allows system to use 2 different memory modules to increase performance and throughput

Single-channel Memory → 64-bit data bus; uses one memory module on one bus
Dual-channel Memory → 128-bit data bus; requires two memory modules and two memory slots on the motherboard
Triple-channel Memory → 192-bit data bus; uses 3 memory modules and 3 memory slots
Quad-channel Memory → 256-bit data bus; uses 4 memory modules and 4 memory slots

In multi-channel configurations, use same model, speed and throughput of memory

ECC Memory (Error Correcting Code) - type of memory that takes parity up to the next level by detecting and correcting an error

Non-Parity Memory - standard memory that does not check for error and allows data to be put in or taken out; very cheap to manufacture and higher speed than parity memory
Parity Memory - performs basic error checking and ensures memory contents are reliable and have integrity; higher reliability but slower speeds

Buffered/Registered Memory - additional hardware (register) between memory and CPU

The motherboard has to support ECC modules and CPU; all modules have to be ECC or non-ECC — having a mixture of both can cause errors

DDR5 modules can still be sold as ECC or non-ECC modules; some have built in ECC

Virtual Memory/Page File - block of space on a hard drive that’s allocated by the OS and pretends to be RAM

Page File or Swap Space - hidden file on a storage device that pretends to be system memory