[lug] memory configurations

Hugh Brown hugh at math.byu.edu
Sat Nov 11 16:25:41 MST 2006

D. Stimits wrote:
> D. Stimits wrote:
>> I'm looking at some advertisements for RAM, and I see there is a 
>> "single rank" and "dual rank" rating (I'm looking at Kingston, don't 
>> know if this is just their own thing or if it applies to DDR2 in 
>> general), and also an x4 and x8 rating. What's the difference between 
>> these, especially with respect to adding to SMP machines?
> Well...reply to my own email. I *think* from what I've found that single 
> rank is better, that dual rank refers to essentially two separate ram 
> modules being on one physical slot. E.G., a dual rank would logically 
> look like two separate slots to the system, and a single rank would look 
> like just 1 logical slot (both would require 1 physical slot). Anyone 
> know if this is basically correct?
> I'm still trying to figure out the x4 and x8 rating, I'm wondering if 
> this is just some latency rating...anyone have an interpretation on the 
> x4 or x8 ratings? Which is better?
> D. Stimits, stimits AT comcast DOT net

We got told by a sales guy that using dual rank meant that you could 
fill fewer slots, but that all of the memory would be directly 
addressable (and also have less total memory).  Single rank you could 
have more but you wouldn't be able to address all of it.

This was with regards to intel woodcrest cpu based machines.

It smacked of sales weasel, so I don't know that I trust it.  I couldn't 
find anything useful on the web, so if there are any hardware types out 
there, I'd be interested in the answer too.


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