Should I get more RAM?

[Skillian]

Slightly theoretical question this one as my pay packet this month is going on a Hyundai L90D+ monitor, but anyway...

I currently have 2 sticks of 256MB PC3200 RAm running in dual channel, but I'm finding it being eaten away with background programs etc. I'm also seeing a lot of hard disk access when I'm playing newer games like HL2.

I think more RAM would help this, but I can only afford to buy 1 stcik of 512MB - this means I wouldn't be running in dual channel anymore (256 + 256 + 512).

So my question is how much performance would I lose going to single channel, and would this "upgrade" actually make my system slower?

edit: Specs:

MSI Delta L mobo
Barton 2500+ oced to 3000+
9800 Pro
2 x 256 PC3200
etc. etc.

[Snee]

You can still run in dual channel using the two 256 sticks I think.

And I don't think it'd make you noticeably slower running anything, and you should see a performance boost when you are running something memory intensive, for sure.

EDits: the two sticks now running dual chan have to be next to each other.

So put them in the first two slots and the 512 stick in the third (or fourth if you have one).


More... I don't know about your mobo but in other cases I know that the first pair of dimm slots had a separate memory controller and the other pair or single slot had another, so for it all to run in dual chan you'd put the 2 256 mems on the first controller and the 512 stick on the other, that way you had the same amount on both controllers and could run it all in dual channel, theoretically.

Not sure if it worked with a different brand of RAM on the other controller, but at any rate it was possible to run the first two sticks in dual chan on those systems, together with a third stick.

[Made more sense of it by adding the words in bold.]

[Spicker]

You can still run in dual channel with the two 256 sticks I think.

No you can't....unfortunately you need even number of sticks

i added a 128mb stick to my dual channel 256x2 and its actually slower, bandwith wise but im sure if u add 512 you should see a big difference

[Skillian]

OK i put this in another forum too and got a similar answer about how i might still be able to run dual channel with three sticks (256 + 256) + 512, which is effectively 512 + 512.

And I have 3 memory slots on my mobo - 2 purple and 1 green, so it looks like it might be possible with the 2 x 256s in the purple and the 512 in the green.

Guess I need to find some specific info on my mobo...

[Snee]

No you can't....unfortunately you need even number of sticks

i added a 128mb stick to my dual channel 256x2 and its actually slower, bandwith wise but im sure if u add 512 you should see a big difference

Just googled it and I don't think these guys would agree with you. For instance.

Based on this article.

EDit: I had it the wrong way around tho', it's the first stick that should be the same size as the other two together.

EDitII: the reason yours can't work is pretty obvious.
256+256 doesn't equal 128, you know.

EDitIII: Skillian, it definitely sounds as if your mobo allows for it, what with them having marked out which slot belongs to which controller and all.

[Skillian]

Thank you guys, especially SnnY.

MSI forums confirm I can run three sticks in dual channel, as long as the two sticks on the first memory controller have the same combined capacity of the stick in the second.

I guess I could have checked there first, but I had no idea it was possible. Good news for me

[Snee]

Cool


EDit: glad you made sense of that, as I feel slightly wreckered and managed to confuse myself when I wrote it.

[Izagaia]

Newbie question (please be gentle) :


What is "dual channel" so far as RAM is concerned? And if there is some sort of performance boost or notable benefit in running it, how do you do so?

[Snee]

How Dual Channel DDR works

Dual Channel DDR works by giving the north bridge two independent controllers to access two sets of memory. To put things in simpler terms, think of a stick of DDR as a two way bridge. DDR achieves double the data rate of normal SDR memory by allowing an independent data path for upstream and downstream travel; much like how a bridge or road works. The theoretical maximum amount of bandwidth for a stick of DDR400 is 3.2GB per second. Like a bridge with a speed limit, the amount of throughput achieved varies depending on the type of data it deals with.

With Dual Channel DDR, the data path is doubled once again by using two sticks of DDR memory. By giving the CPU/north bridge another data path to the memory, bandwidth is effectively doubled, giving Dual Channel DDR400 6.4GB/s. In simple terms, think of DCDDR as widening the bridge by adding two more lanes. This effectively allows more data to travel faster; much like traffic moving faster when there’re more lanes to drive in. The downside to this is traditional DCDDR solutions require pairs of same sizes.

In more technical terms, DDR memory is 64bit and communicates with the CPU/north bridge at 64bit. Dual Channel DDR can operate in two modes. One mode is it accesses the memory in 128bit mode, which is how most DCDDR chipsets operate. The other mode is it communicates with the two memory controllers in 2x64bit mode, treating each controller individually.

source

Basically it can double the bandwith at which the memory is accessed by when treating them as a unit, or it can access modules independently in a more effective way than on non-dc systems.

It requires them to be matched as described in this thread tho'.

Exactly how big a noticeable gain you get by running your memory modules in dc I can't tell you as there appears to be different results for different tests. It'll give you summat faster access times tho', this is without a doubt.

[BILLY-THE-FISH]

Sorry to hijack thread... but i have a Ram question too

Sorry its a bit noob, I want to install another 512Mb of Ram in my motherboard (Asus P4S533-E) but not sure which slot to put my extra (with 512 I have got at the moment) Ram in? I have no motherboard Manual and can't seem to find out on web anywhere. Does it matter which of the other slots (out of the 2 spare) I put it in?

Cheers