2GBx2 vs 1GBx4 - "Interesting" Theory?

[chjade84]

I found this somewhere, but I can't help think how this makes no sense at all.


When you go from Four 2 gb sticks down to Two 2 Gb sticks
you must realize that you just removed 50% of the wires going
into your ram bank... half the lanes ? half the traffic...

if you really want to test 8gb ram usage verses 4 gb ram usage
Try it without reducing the paths into the ram bank by 50% !

try installing "Four - 1 Gb sticks " to compare the performance
of an 8 gb system vs a 4 gb system using the same amount of
wires going into the ram bank for both modes. then you will
probaby see that using 4 gb of ram in 4 sticks is just as fast
as using 4 gb of a 8gb bank also in 4 sticks.

the reduction in performance you are seeing by removing two
of the 4 sticks of ram is due to a 50% reduction in physical
wires going into the ram bank, NOT because some ram is gone
that you assumed your system was using.

I am designing 2 computers right now for a chiropractors offics.
as usual I use all available ram slots in every machine I build,
because test prove that using four 1gb sticks is a faster bank
than using two 2gb sticks or worse even !! ONE 4gb stick !


I can't imagine... Am I wrong?

 

[sub mesa]

As far as i understand, the memory controller in recent processors (IMC) allow dual-channel (128-bit) or triple-channel (192-bit). You would need a quad-channel (256-bit) IMC to really gain anything by using 4 memory modules.

Also know that some modules have 2 banks (one on each side of the memory module). This would allow dual-channel (128-bit) with only one module, i would guess. Perhaps others can comment on this.

But i do not believe you have anything to worry about using 2 modules. Its not that improving bandwidth reduces the memory latency- you can only enhance performance by parallel operation so the memory performance benefit would be 0% to 100% depending on application.

 

[ewood]

this guys "theory" is completely false. Since there are only 2 and 3 channel memory controllers no benefit can be seen going from 2x2gb to 4x1gb or 3x2gb to 6x1gb. Going from one to two sticks can make a difference though since two sticks are required to utilize bith channels. I have not heard anything about one stick being seen as two channels because of the stick having two banks. I'm pretty sure you have to have two physical slots populated to have the ram operate in dual channel mode.

 

[chjade84]

Well I agree that this doesn't seem right. I think he's trying to say that if you have 4 modules instead of two, data can be sent along different paths (modules 1, 2, 3 and 4) instead of just 1 and 3. Kind of like having a gun with two barrels instead of 1 - even though they have the same clip size. You can fire twice as fast as the single barreled gun.


Hell if I know. I've never populated all the slots just "because" and I've never heard of anyone else doing it. I just figured I'd ask here because who knows.... maybe I missed the memo.

 

[mindless728]

2 vs 4 sticks doesn't matter speed wise as some above have stated, most systems are dual channel (quad would be needed for 4 sticks) and some triple channel

@chjade84, i have all 4 dimm slots filled, and i can tell you there is no difference

if anything it might be a tad slower since the MC has to do more work with 4 sticks than with 2