Memory RAM - slot placement

Have some new RAM on its way for an AM3 build.

However, the cooler I'm using overhangs the first slot - am I right in saying that RAM has to go in slots 1 and 3 before filling up 2 and 4? The motherboard is an Asus M4785TD - M EVO.

 

Pretty sure you can use either pair independently.

 

In the mobo manual it states

"Supports one pair of modules inserted into either the blue slots or the black slots as one pair of dual channel memory configuration"

This suggests to me that either slots 1+3 or 2+4 are fine to use.

 

All my ASUS, AMD boards supported that config. 1+3 or 2+4.

 

I had an inkling that the above posters were incorrect, so I downloaded the manual in order to double check.

This layout is very different to the one I usually encounter with Intel and I think the majority are accustomed to Intel's layout as well.

This picture gives the clearest answer:



It seems that AMD DIMM slot nomenclature is as follows:
DIMM A2 (Ch. A) - DIMM B2 (Ch. B) - DIMM A1 (Ch. A) - DIMM B1 (Ch. B)

This means that the complementing DIMMs for dual channel are next to one another. Given that your cooler is overhanging DIMM slot A2, it would appear logical that you should use slots A1 and B1 (i.e. slots 3 and 4, the pair farther away from the CPU socket).

Hopefully this will work for you. But as always, "In theory, theory and practice are the same. In practice, they are not". Once you fire up your system, just check the 'Memory' tab in CPU-Z and it will verify whether or not your sticks are in dual channel.

 

My instincts would have been to put pairs in colours. The image suggests different?

 

Does make sense.
Put the pair onto the same colour. Each will be on a different channel. Thus dual channel and double data rate.

Or am I more sleepy than I think I am and am spouting rubbish?

 

Image says channels cross colours
Channel A, I presume is a pair on 1 and 3 - diff colours?

 

FYI, I put it in slots 2&4 and it seems to have worked perfectly! Good times!

 

Slots 2 and 4 are on the SAME channel according to the picture posted by Kodongo above. That should mean they are running in SINGLE channel mode.

 

You mean dual channel. Single channel is when you use 1 module per channel.

 

No, I mean single channel. Single channel is when you use a single channel, dual channel is when you use two channels. He has both modules in the same channel, so he's using a single channel. I don't know for sure, but it makes sense this way.

 

Correct, for this board we advise populating the two Blue DIMM slots for optimal compatibility and stability. Also as you are running with both DIMM populated then you are getting dual-channel.

 

Unfortunately for you, no, it doesn't work like that.

Single channel is when you have one module in one channel. If you got two identical* modules in two different channels, both work in single channel mode.
Dual channel is when you have two identical memory modules in one channel. If you got four identical modules in two different channels, then you got two dual channels.
Flex mode is when you have two memory modules in one channel with different memory sizes. The part of the channel which equals to the smaller of two modules works in dual channel mode, the rest works in single channel mode.

*identical = same size

In other words - single channel = standard bit width of the memory module, dual channel = doubled bit width. So for example if specific memory interface has 64-bit interface with one module, then it can run with 128-bit interface with two modules.

For more info please check out http://en.wikipedia.org/wiki/Multi-channel_memory_architecture .

 

Guys!

This is still causing me BSODs!

I'm very confused. What I'd like to know is:

For dual channel, do both memory sticks have to be in the same channel, or different channels?

Because right now, I can run with one stick in without a problem, but as soon as I put another stick in, the computer either won't boot up or BSODs in P95s memory test.

Its nothing else, I've literally updated the firmware in everything, and P95 CPU test runs fine. However, with two sticks in, P95 CPU/MEMORY test fails within seconds. Also, BF3 BSODs the computer too with a Memory Management error.

EDIT: Oh and FYI, the memory I have is 1600Mhz - do I need to slow this down to 1333Mhz? I read here that AM3 CPUs don't like 1600Mhz memory?

EDIT x2: Traditionally it appears that RAM should go in slots of the same colour, but on this board it appears that memory should go in slots of DIFFERENT colours?

 

And to update, running in slots A2 and A1 CPUZ reports I am running in SINGLE channel mode.

 

BUT: if I place RAM in A2 and B2 (both black) I get BSODs - which I dont seem to get in single channel mode.... testing now.

 

Sounds to me like it might be faulty RAM.

Slots A1 and A2 should give dual channel according to that manual.

I'd try and check to see if the RAM is faulty, could be the RAM is incompatible, if you can slow it down to the 'default' speed for the CPU that should eliminate that.
There's not any dual/single channel settings in the BIOS you have to set is there?

 

Ok, I've tried two different sets, and I seem to get a BAD_POOL_HEADER BSOD in Dual Channel (Unganged) mode. Ganged mode makes no difference.

Can anyone read crash dump files if I post them?

 

That's only useful for Microsoft, and only for debugging Windows kernel bugs.