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Old 11-27-2011, 03:10 PM
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Jeffk Jeffk is offline
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Default banks, ranks, & single-/double-sided RAM: a theory dilemma

I'm studying for my A+ & am trying to get my head round the relationship between memory banks, memory ranks & single-/dual-sided memory.

Reading around, it seems that 'banks' is used in similar but subtly different ways:

1) as a group of sockets or modules that make up one logical unit, with the logical unit referring to a match between the processor's data bus width and the RAM's bit width e.g. one 64-bit DIMM or two 32-bit DIMMs makes a full bank with a CPU with a 64 bit data bus.

ok, that makes sense

2) but then other people refer to banks of memory addresses

3) & then Scott Mueller (page 334) says that dual-ranked memory has internal banks of memory chips called ranks.

He was explaining why single-/double-sided memory has nothing to do with whether there's chip one one or both sides of a RAM stick, it's to do with memory ranks.

I think my brain's gonna explode!

Any help from the more theory inclined techs here would be much appreciated. Thanks!

Also, which is faster, single- or dual-rank (often called single-/double-sided memory)?

(Hopefully it won't be too long before I can contribute to the forums by answering others' questions!)

Last edited by Jeffk; 11-27-2011 at 03:16 PM. Reason: forgot something
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Old 11-27-2011, 05:35 PM
tek9 tek9 is online now
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According to Jean Andrews' A+ Guide:
Single sided and double sided refer to the chip placement on the modules: single sided have the chips only on one side of the module, and double sided have them on both sides.
Memory "Ranks" refer to how many 64-bit banks are provided. Single ranked DIMMs provide one 64-bit bank, which matches what the CPU can handle, as you wrote in the beginning of your post.
Single ranked are "better performing" than dual, quad etc. She doesn't say if it's "faster".
Hope this helps somewhat.
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Old 11-27-2011, 05:43 PM
Encrypted Existence Encrypted Existence is offline
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Single or double sided is exactly what it sounds like (If there are memory chips on one side...single sided. If there are memory chips on both sides...double sided).
A bank is the the memory that a processor addresses at one time (64 bits these days).
Double-sided DIMMS (have memory chips on both sides) that provide two 64 bit banks are said to be dual ranked.
Single-sided DIMMS (memory chips on one side only) are ALWAYS single-ranked (they only have one bank).
Rank refers to the amount of banks the memory module has.
Double-sided DIMMS can be single ranked.
Single ranked DIMMS are faster.

Tip: remember that double-sided refers to the physical location of the memory chips and dual ranked refers to how the memory on the DIMM is addressed.

Thanks for giving me an opportunity to crack open my A+ study material. I used the Professor Messer videos and the Jean Andrews Comptia A+ Guide to Managing and Maintaining Your PC. The above came directly from that book. Hope this helps.

Edit: Tek9 beat me. Good info.

Last edited by Encrypted Existence; 11-27-2011 at 05:59 PM. Reason: addition
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