why do some dual channel motherboards have 4 slots

[da na]

Some motherboards that only support dual channel memory have 4 slots... why?

For example, the Asus M3n78-EM has 4 slots but only supports dual channel

[Moonzy]

enjoy the next hour or so

 

[Guest]

Because you can have two pairs of dual channel RAM for quantity.

[NelizMastr]

A channel can contain more than one DIMM, That's why.

 

Servers were quad channel for many many years, they didn't come with 4 slots though, many had 8-16.

Triple channel capable servers often had 12 or even 24. HP had 18 slots in their servers, at least.

[Oshino Shinobu]

Channels and DIMM slots are different. 

 

On a dual channel board with 4 slots, there are two slots per channel.

[da na]

Just now, NelizMastr said:

A channel can contain more than one DIMM, That's why.

 

Servers were quad channel for many many years, they didn't come with 4 slots though, many had 8-16.

Triple channel capable servers often had 12 or even 24.

ahh, so I could put 4 sticks in it in dual channel? thanks!

[Stahlmann]

You can use either 2 or 4 sticks and both will run in dual channel. But of course you can achieve much higher capacity with 4 DIMMs. And then there's also the conversation of dual and single rank, but that's another story worth a 2 hour rambling video.

 

Most people are fine with 2x 8GB DIMMs for a total of 16GB.

[FRD]

I also didn't know about this a few years ago. Back then my friend told me I could run my 4 sticks of DDR3 memory in quad channel, just like "his". It turned out his information was wrong. I was always wondering too why my CPU-Z showed Dual channel even though I was using 4 sticks. It also could be because he was on the LGA 2011 platform, not sure.

[NelizMastr]

4 minutes ago, wat3rmelon_man2 said:

ahh, so I could put 4 sticks in it in dual channel? thanks!

As long as both channels are populated identically, yes.

 

I.e. 2x2GB in each channel for a total of 8GB.

[Moonzy]

1 minute ago, NelizMastr said:

As long as both channels are populated identically, yes.

 

I.e. 2x2GB in each channel for a total of 8GB.

You can do 4gb + 8gb

It'll still run the first 8 gb in dual channel and 4 gb in single channel

 

The video I linked explained all these and more, thus why it's an hour long

[da na]

13 minutes ago, NelizMastr said:

As long as both channels are populated identically, yes.

 

I.e. 2x2GB in each channel for a total of 8GB.

That is what I will do - this is for an AM2 build that will be a system for retro gaming, currently running 2x2gb ddr2 664. I'll put 4x2gb OCZ ddr2 800 in it for more speed/capacity

[NelizMastr]

3 minutes ago, wat3rmelon_man2 said:

That is what I will do - this is for an AM2 build that will be a system for retro gaming, currently running 2x2gb ddr2 664. I'll put 4x2gb OCZ ddr2 800 in it for more speed/capacity

Going beyond 4GB is not very useful if you're aiming for a 32-bit operating system like XP or older, though.
If that's what you're going for, stick to 4.
The benefit of a 32-bit OS is backwards compatibility (to some degree) of 16-bit apps/games.

[da na]

31 minutes ago, NelizMastr said:

Going beyond 4GB is not very useful if you're aiming for a 32-bit operating system like XP or older, though.
If that's what you're going for, stick to 4.
The benefit of a 32-bit OS is backwards compatibility (to some degree) of 16-bit apps/games.

Aiming for Win Vista - mid 2000's system.

[FRD]

20 hours ago, WikiForce said:

server grade boards do support quad channel memory for a very long time and iirc recently 6 channel is now a thing too, btw we might get quadchannel with ddr5 on consumer grade that too with two sticks if rumors are true

I didn't know about the server grade part, since I'm not into that. I hope DDR5 indeed gets it for us consumers. Last year I almost decided on buying a Threadripper along with a motherboard, so I could run my first quad channel ever. In the end I didn't go for it anymore, since it was overkill for a gaming PC, even for my workstation use.

[da na]

1 hour ago, FRD said:

I didn't know about the server grade part, since I'm not into that. I hope DDR5 indeed gets it for us consumers. Last year I almost decided on buying a Threadripper along with a motherboard, so I could run my first quad channel ever. In the end I didn't go for it anymore, since it was overkill for a gaming PC, even for my workstation use.

Yeah... in my HP z620 workstation I'm running 8-channel memory over 12 slots with two Xeon e5-2690 CPUs. Pretty unique to be running 8-channel as pretty much no one else does.