Fitting DDR2 memory - which slots best?

  Domza 12:41 17 Feb 2006

I have a Dell with a Pentium 4 (520) processor on a 915 chipset.

Up to 4GB of DDR2 memory are fittable in 4 slots.

It came with 256Mb in slot one when I bought it. I subsequently added another 256Mb module a couple of months after and fitted it in the adjacent slot on the board thinking I would then benefit not only from more memory but from the dual channel function which is supposed to be better.

This is the wierd bit - when I run Belarc advisor on my PC it says
Slot 'DIMM 1' = 256MB
Slot 'DIMM 3' = Empty
Slot 'DIMM 2' = 256MB
Slot 'DIMM 4' = Empty
(in that order on the page)

But I happened to be in the BIOS the other day and the BIOS told me that 256Mb modules were installed in slots 1 and 3, and therefore dual channel memory funtion is not active.

Regardless of this I have just bought an additional 512MB module this morning as I'm finding I need more than the 512 I've got.

My question is - can anyone tell me which of my 256, 256 and 512MB modules should go in which slots on the motherboard, to give me the best use of my memory?

  Eric10 14:40 17 Feb 2006

For dual channel operation it is normal for matching dimms to be fitted in slots 1 and 3 then 2 and 4. Normally you can use 1 dimm (single channel), 2 dimms or 4 dimms (dual channel) but not 3 dimms as the system then doesn't know what you expect of it. But then Dell sometimes make up their own rules.

  Domza 16:14 17 Feb 2006

Hi Eric10.

I put the new 512MB in slot 'DIMM 1' and left 'DIMM 2' empty, and then matched the two 256MB modules as a pair in 'DIMM 3 & 4'. Powered up the computer, and it booted normally and now is showing as having 1.0GB of memory!

I don't know if this is necessarily the optimum configuration for taking full advantage of these 3 modules but as it works I'm not going to mess about with it.

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