A question about DDR2 RAM....

**Crian** · 05-17-2007, 03:34

There's single channel, and dual channel, right? Could anyone knowledgeable on this please explain the difference between the two? And under which setups are they best?

I want to get more RAM for my comp but I want this clarified first before I do anything, thank you.

**Lemur** · 05-17-2007, 04:59

When available, dual-channel is always better. Basically, hrm, what's the easiest way to explain ...

Your CPU is very, very fast. The channel it uses to talk to the RAM is slow by comparison. Any tricks the motherboard can use are helpful; dual-channel architecture is such a trick. It accesses pairs of RAM as, well, two channels instead of one.

I'm having a hard time putting this simply. Here's a primer on how dual-channel works. Trust the wiki, not the lemur.

**LeftEyeNine** · 05-17-2007, 08:10

Trust the Wiki, and the Lemur.

P.S. Dual DDR means double bandwidth availability as you insert two identical DDR RAM modules, instead of a single one.

**Husar** · 05-17-2007, 12:07

How about four modules? Can they run in Dual-Channel mode as well?
I'm thinking about one of those new mainboards with four slots and four times 1GB modules, would that result in two modules sharing one channel or so?

**Lemur** · 05-17-2007, 14:56

Originally Posted by Husar

How about four modules? Can they run in Dual-Channel mode as well?

As long as they are installed in matched pairs, there's no reason not to run them dual-channel. But as far as the mobo and CPU are concerned, it will still be a situation with two channels, not four.

**Crian** · 05-17-2007, 16:00

I... sort of understood the wiki...

Thanks for the reply Lemur... I was getting suspicious about my system underperforming.

So in my current setup (sig), my RAM is effectively causing a bottleneck in my system, is that right?

I want to upgrade to 2 GB DDR2 667 dual channel, and those would be the ones labeled with "(2 X 1GB) DDR2"... right?

OR is it simply sticking in 2 sticks and tweaking the BIOS?

EDIT: Oh and do I need some special setup in my motherboard to get this to work? Or do you just plug this in like most RAM sticks? And do I have to set this up in the BIOS or will it automatically run itself dual channel? My board has 4 DDR2 memory slots.

**Slug For A Butt** · 05-17-2007, 20:49

Check your motherboard info to make sure that it will support 667 RAM, and you will probably have to change the BIOS settings to run in dual channel mode.

**Crian** · 05-18-2007, 01:30

Slug: Thanks and yes, my motherboard supports up to 667 DDR2 and it has up to 4 memory slots. Are dual-channel RAM modules conveniently labeled as such?

**LeftEyeNine** · 05-18-2007, 12:20

Dual DDR is not a feature based on RAM module, it's a motherboard-supported feature.

That means if you have one DDR module installed on a Dual-DDR-supporting motherboard, you may start using the technology as soon as you install another RAM module (one which is almost identical with what you have, say, you must have two Twinmos 512 MB DDR RAM 400 MHzs in the end).

But, aware of this dual DDR tech, RAM manufacturers offer Dual Pack RAM modules, two identical modules in one package to make use of Dual DDR error-free.

**Crian** · 05-18-2007, 15:09

I See

.

Thanks LEN! 'Tis the second time I got help from you

. Fortunately for me, the Intel 945P chipset in my board supports dual channel memory.

So for the last time (really sorry if I'm starting to get irritating

), I'll just have to get an exact same memory module as the one I already have (Or buy two completely new 1GB DDR2 667s).... plug it/them in the slot/s, then tweak the BIOS for the rest of the magic, right?

Again thanks everyone!

**DukeofSerbia** · 05-18-2007, 22:30

Originally Posted by LeftEyeNine

Dual DDR is not a feature based on RAM module, it's a motherboard-supported feature.

Only in Intel based systems. AMD has memory controller in CPU.

Originally Posted by Crian

So for the last time (really sorry if I'm starting to get irritating

), I'll just have to get an exact same memory module as the one I already have (Or buy two completely new 1GB DDR2 667s).... plug it/them in the slot/s, then tweak the BIOS for the rest of the magic, right?

Plug memory in 'the same color' slot [see instruction book].

**Crian** · 05-19-2007, 06:11

Alright! Thanks Duke of Serbia.

**DukeofSerbia** · 05-19-2007, 08:39

I forgot: buy another Apacer 1GB DDR2 533 model. Yes, you can buy faster memory but it's useless as the memory speed will work ALWAYS as the speed of the slowest model (the same story with hard disks in RAID).

If you want faster memory, you need to buy the new pair, and sold that Apacer.