Single Rank or Dual Rank Memory

[troy]

Can anybody please tell me the meaning of dual rank and single rank memory?
Thank you

[ApPy10]

Dual Rank means there are chips on both sides of the dimm and Single Rank is single a dimm with chips

[EINSTEIN_007]

Single-Rank/Dual-Rank Server Memory Explained

Memory Ranks - Intel E7320/E7520 Chipset-based Servers

The new servers utilizing Intel's E7320/E7520 chipset (code-named "Lindenhurst") support PC2100, PC2700, and PC2-3200 memory. Memory Ranks limitations apply only to PC2700 and PC2-3200.

Q: How do Intel Lindenhurst servers limit ranks?

The number of ranks is important based upon the server's memory speed:

• If PC2100 memory is used, the number of ranks is not critical and either single- or dual-rank memory module pairs can be used.
  
• If PC2700 or PC2-3200 memory is used, there is a maximum of 8 ranks per server. For example, if two pairs of dual-rank memory modules are inserted into the memory sockets, that would add up to 8 ranks (4 modules x 2-ranks each = 8 ranks); in this case, empty sockets cannot be used for upgrading memory.

More here: http://67.91.114.164/server_memory_ranks.htm

[T.J.]

See This. It looks like the ranking has something to do with memory chips being on both sides of not. I am sure if that isn't correct someone else would chime in.

[techzilla]

Dual Rank has nothing to do with 'sides', other than the fact that many times it uses both sides. You can have dual or even quad rank with chips only on one 'side'.

Ranks are addressed in parallel, it's done to raise overall capacity without increasing the chip size. Motherboards, especially server motherboards, can be picky about which is preferred.

For example, a mother board that can do quad channel, when all slots are filled with DDR3 DIMMS. Except it might only work with single or dual rank. When you put in quad rank, it boots everything works as expected.... except your motherboard will only allow addressing in dual channel mode. So for best compatibility you need to make sure you get the proper ranked ram.

The above posted explanation is somewhat misleading, check Wikipedia has for the most correct explanation I've seen.