A simple question about RAM

[kritonas]

If i have 2 identical sticks of 512mb ram each, in a motherboard that supports it, they will work in dual mode (if installed correctly)

Now, if i have 3 identical sticks of 512 ram each, will the two of them work in dual mode? or will all 3 work in single mode?

thanks!

 

[Mictlantecuhtli]

Three will work in single-channel mode. As far as I know, you can't have both single- and dual-channel memory modes at the same time.

 

[Vigilante]

Interresting question. Some motherboards have 4 slots, I would think you could have dual channel with two on each side.
Yet other motherboards have 2 slots and then an offset single slot. I would think with this arrangement you could have the 2 slots filled and still have dual mode with the 3rd one.

In other words, they give an odd number of slots and say it's dual channel? Or "if you want dual channel, use only 2 or your 3 slots". That doesn't sound right.
I'll have to look in to it, unless someone else knows offhand. Cause I might buy a 3rd stick, but not if it knocks my dual out.

Let me ask this, then: Would it be better to have 1gb as dual channel? Or have 1.5gb as normal?

 

[DonNagual]

To add to the equation. My motherboard's manual says the following options are supported:

a: one module insterted into either of the blue slots, in a single channel memory configuration
b: one pair of modules insterted into either the blue slots or the black slots as one pair of Dual-channel memory configuration
c: 4 modules inserted into the blue and black slots as two pairs of Dual-channel memory configuration

So it appears that yes (at least in my case) if I have 4 modules, they do run in dual mode.

I suppose the question is motherboard specific, but in my case, not only will 3 modules run in single channel mode, but they are not even supported (i.e., may not even work) on my motherboard. (A8N-SLI deluxe).

 

[kritonas]

Let me ask this, then: Would it be better to have 1gb as dual channel? Or have 1.5gb as normal?

that was exactly what i meant to ask, thanks

 

[Vigilante]

Well let me try to answer my own question then. lol

I would take a survey of your system as it is now. Find out, as close as you can, if you even come CLOSE to filling up that gig as it is.

That being said, if you can actually FILL a gig, then 1.5gb in single mode would probably be better. But if you DON'T fill that gig, or come close, then purhaps the added function of dual channel is more of a performance gain then having more RAM.

 

[Mictlantecuhtli]

I'd get as much RAM as possible. The difference between single- and dual-channel memory speed isn't that big, in my opinion.

nForce2: single-channel mode vs. dual-channel mode

The Battle of the Channel - Dual vs Single

Dual Channel

Yes, some synthetic benchmarks, like SiSoft Sandra, show 60% difference in memory bandwidth, but only because the memory test is engineered to measure just that.

More RAM could reduce loading times after the first run, if the operating system can cache things efficiently.

Still, some applications insist in having a pagefile, no matter how much free RAM you would have.

 

[Vigilante]

This was quoted in one of your links:

"What if you have three modules? I’m sorry, but you’re out of luck. Dual Channel requires either two or four modules. What you have is three modules trying to all use the same single memory channel. "

I would have guess as much.

And then these quotes from another:

"Professionals who work with graphics and large documents could definitely use the boost in bandwidth, as they push wall-sized posters at print resolution around in Photoshop, or model entire cities in Maya, but most users will only notice small performance increases in a small number of applications."

"That fact, coupled with memory prices being at an all-time low in their notoriously ephemeral price cycles, leads us to formulate this cautious advice: get a Dual Channel setup now if you can, because by the time applications and games have caught up, and require both barrels of the RAM shotgun, you’re most likely not going to be able to afford it."

Also, if you have a system using integrated video, you would WANT the dual channel, as it can help bring the performance back up again.

Now I just have to figure out what my own options are...