Memory Question...

[m33pm33p]

Ive been reading a lot lately about memory and how it works. One question I still have though is this.

If a MOBO states that it accepts up to dual channel, and you purchase a triple channel kit, are there any side effect/negatives that will occur? Or is it just only going to run at the dual channel level?

 

[brencat]

If your motherboard accepts DDR2, that is all you can use. You cannot use DDR3 in a DDR2 motherboard, just as you cannot use DDR2 in an older DDR socket motherboard...or vice versa.

Go to the website of the motherboard manufacturer to find the RAM kits that work with your model #.

 

[alaricljs]

Dual channel will only operate with an even number of sticks and each slot pair must contain the same size/density module. I hope you can extrapolate tri-channel requirements from what I just said.

 

[FishAk]

By definition, a triple channel kit will come as three sticks. If you use it in a board that supports dual channel, in most cases two of the sticks will run in dual channel, and the other will run single channel. If you buy one more module that is the same as the other three, the board will run the four sticks as a pair of dual channel sets. Check the supported vender list for the specific motherboard.

 

[alaricljs]

By definition, a triple channel kit will come as three sticks. If you use it in a board that supports dual channel, in most cases two of the sticks will run in dual channel, and the other will run single channel. If you buy one more module that is the same as the other three, the board will run the four sticks as a pair of dual channel sets. Check the supported vender list for the specific motherboard.

Dual channel does not work with odd numbers of populated slots. Both channels need to be populated in an identical manner.

Triple channel is much the same in that all 3 channels must be populated identically for it to function.

 

[m33pm33p]

If your motherboard accepts DDR2, that is all you can use. You cannot use DDR3 in a DDR2 motherboard, just as you cannot use DDR2 in an older DDR socket motherboard...or vice versa.

Go to the website of the motherboard manufacturer to find the RAM kits that work with your model #.

I know this. I was asking about dual/triple. Which Im pretty sure is completely different from DDR2/DDR3. In any case I think you guys confirmed what I thought, just have to make sure its on the MOBO supported list. Thanks for the help.

 

[FishAk]

Dual channel does not work with odd numbers of populated slots. Both channels need to be populated in an identical manner.

Triple channel is much the same in that all 3 channels must be populated identically for it to function.

This is what I said.

However, I went a step further and said if you populate three slots on a two channel controller with equivalent modules, on most boards, two sticks will run in dual mode, while one stick will run in single mode. Is this true, or am I mistaken?

 

[alaricljs]

Not true. To keep it simple they implemented it thus:

When correctly populated for dual (or triple) channel, all addressing gets re-mapped. There's no "processor" to say if we have "some" dual channel use this map, and no way to calculate mapping on the fly. There's just 2 maps. 1 is linear across all present memory, the other is round robin between the 2 channels. If the 2 channels aren't equal size, round robin will start hitting non-existent addresses.

 

[FishAk]

Thanks for correcting me, alaricljs. Apparently, only motherboards with the nForce2 chipset can run two sticks in dual with one in single mode; and they only have three slots.

 

[alaricljs]

Well, never knew that myself about that chipset. I know Intel chipsets don't do that.

 

[Wolfpup]

I've never been 100% sure about this-can modern chipsets handle having SOME RAM be dual (or tripple) channel while at the same time some is single channel-so I guess randomly some memory locations would be faster than others?

I've been told by multiple people that that's how it works now, though I'm used to it being that you're either in dual channel mode or your not.

Either way though, if your setup supports dual channel, then only by DIMMS in pairs-don't get a 3 DIMM package, get 2 DIMM packages. And of course if you support tri-channel, then only buy RAM in 3s.

 

[tweakboy]

Guys I think he can use DDR3 on a DDR2 motherboard. Depends what mobo he has.

On my ASUS when I go to BIOS memory config it lists up to 1949Mhz and 1:1 is what Im using.

 

[FishAk]

While some motherboards do support both DDR2 and DDR3, it's because they have a couple of each slot type. I don't think there are any which allow you to use both types at the same time.

The sticks are physically different, i.e. the notch is in a different position.

 

[alaricljs]

Only if his mobo has both DDR2 and DDR3 slots, they have a different spot for the locator cut-out.

 

[hanspeter]

Not true. To keep it simple they implemented it thus:

When correctly populated for dual (or triple) channel, all addressing gets re-mapped. There's no "processor" to say if we have "some" dual channel use this map, and no way to calculate mapping on the fly. There's just 2 maps. 1 is linear across all present memory, the other is round robin between the 2 channels. If the 2 channels aren't equal size, round robin will start hitting non-existent addresses.

Try checking out Intel's flex mode