Which DIMM slots to use?

[Peter Wertz]

I am building on ASUS H170 Pro Gaming motherboard that has four DIMM slots. The ASUS Pro Gaming Guide recommends if using two DIMMs, insert one in DIMM_A2 and one in DIMM_B2.

I have read several posts that indicate the Guide is incorrect and my experience has been to use lower numbered slots first, i.e. A_1 and B_1.

Other than trial and error, is there a way to tell which slots to use? Thanks. Peter

 

[nerp]

I have the same board and I put them next to each other in the first two DIMM slots of the same color. I plan on adding two more sticks of the same capacity so it won't matter in the long run but now I'm wondering if I messed up and am hurting performance.

 

[mikeymikec]

It's been years (possibly a decade) since I encountered a board that acted weirdly because I put compatible and fault-free RAM in the wrong slots. I tend to use the slots closest to the CPU first, and if I'm installing two modules I double-check the manual to find out how it likes modules to be installed to get dual-channel working. I also check the BIOS to make sure the modules are listed as running in dual channel mode.

Like nerp I tend to go with slot colours but I have encountered boards whereby dual-channel is only achieved by 'pairing' modules up in slots of differing colours (MSI IIRC).

 

[LTC8K6]

If you are not using an igp, then it doesn't really matter. You'll never notice any difference unless you pay close attention to benchmarks.

 

[Peter Wertz]

Thanks for the responses. Nerp - I think the User Guide is clear on the recommended configuration for a matched pair like you have now. One goes in the same color slot in DIMM A and one in DIMM B. Regards. Peter

 

[Auric]

ASRock likewise specifies populating A2 & B2 first.

 

[MongGrel]

The manual is the way to go. If you want dual channel.

Still use DDR3 triple channel in this thing I guess.

It's not like the guys that engineered the thing have no idea how it operates, now is there

 

[VirtualLarry]

I have the same board and I put them next to each other in the first two DIMM slots of the same color. I plan on adding two more sticks of the same capacity so it won't matter in the long run but now I'm wondering if I messed up and am hurting performance.

I initially screwed up with my ASRock Z170 Pro4S.

I, by default, always put two DIMMs into the first two slots closest to the CPU. At least back in the DDR(1) days, that was the way to do it.

But apparently, you have to put the RAM into slots 1 and 3, if you only have two sticks, in order to activate dual-channel mode.

I didn't notice much of a performance difference, though, once I was finally in dual-channel mode on that board.

 

[Magic Carpet]

Personally, I try to stick to the guidelines as pointed out in the user manual. It can be 1,2, 1,3, 2,4 or 3,4. At any case, it won't explode your computer by doing it wrong. Experiment, benchmark, report

e.g. This manual for an MSI board suggests this order (but I tried 1,2 and it still worked in dual-channel = but I ended up leaving it 2,4 as the manual suggested):