Which are the best DIMM slots to use to add more RAM?

Ady2009 · 23 May 2023 at 00:11

I have a 10 year old intel motherboard that I want to add some extra RAM to. It currently has two 4Gb DDR3 sticks installed and I have got two 8Gb sticks that I want to add to it to give a total of 24Gb.
I am confused which slots would be best to use on the board for each stick of RAM.

The slots available are:
DIMM 3 (Channel A DIMM 0)
DIMM 1 (Channel A DIMM 1)
DIMM 4 (Channel B DIMM 0)
DIMM 2 (Channel B DIMM 1)

The only thing I can find in the manual is - For best memory performance always install memory in the DIMM 1 and DIMM 2 sockets if installing only two DIMMs on your board.
Should I put the 8Gb pair on the same channel or DIMM number (0 or 1).

I was thinking to set it up as follows:
DIMM 3 = 4Gb
DIMM 1 = 8GB
DIMM 4 = 4Gb
DIMM 2 = 8Gb

Orcvader · 23 May 2023 at 13:13

Assuming 1 and 2 allows the RAM to run in dual channel mode then yes, the planned setup you have looks about right.

I would be more worried about speeds and timing compatibility, you might need to reset the BIOS first to ensure it runs at standard JEDEC speeds before you try to enable XMP, if available.

Ady2009 · 23 May 2023 at 13:58

Ok, I think I am understanding it now. It is a single bus that is split into 2 channels and must be balanced for it to work properly.

This is from the manual,
Dual channel (Interleaved) mode. This mode offers the highest throughput for
real world applications. Dual channel mode is enabled when the installed memory
capacities of both DIMM channels are equal. Technology and device width can vary
from one channel to the other but the installed memory capacity for each channel
must be equal. If different speed DIMMs are used between channels, the slowest
memory timing will be used.

As long I equally distribute an 8Gb and 4Gb stick between each channel then it should work at its best.

Does it matter if either the 8Gb or 4GB comes first in a channel. For example, I could put the 8Gb stick in either Channel A Dimm 0 or Dimm 1 with the 4Gb stick going in the other Dimm slot. I would assume that it is best to put the biggest stick of RAM in the first DIMM but I could be wrong.

pepp77 · 23 May 2023 at 14:05

Put the 8GBs in 3 and 4 and the 4GBS in 1 and 2. This gives you the hight capacity in the primary slots.

Ady2009 · 23 May 2023 at 14:41

Perfect. Thanks for your help. It is a learning experience tinkering with computers.

Tetras · 23 May 2023 at 16:01

Ady2009 said:
I have a 10 year old intel motherboard that I want to add some extra RAM to.

What is it?

Ady2009 · 23 May 2023 at 16:29

It is an Intel DQ77CP which is nothing fancy but it is a reliable old workhorse