single/dual channel RAM

[dOwnsizer]

typically, when drooling over parts, I go to newegg, and intend on purchasing my next rig from them.... I've decided to upgrade my current box with a 2nd gig of RAM.... being the impatient person I am, I figured I'd stop by the TigerDirect outlet by work after getting paid on Wed....

I know my machine uses DDR2/533 PC-4200 RAM...

I looked at TD's webpage to get an idea of what I wanted, and noticed they have both single and dual channel 4200 RAM (only site I've been to that distinguishes single/dual channel)

How the heck do I tell if I need single or dual channel?

I've already checked pc manufacture's page, and my motherboards page, and both just say PC-4200

here's a list of specs (at least relevant ones), just in case I missed something *taken from powerspec webpage*

CPU: Pentium D 820 (2.8)
Motherboard: ECS RC410-M
RAM: 2x512MB PC-4200/533mHz ECC (2x512)

[Natt]

Dual channel ram is a matched pair of ram, so 1gb would be 2x 512mb sticks.

[Vreki]

From Wiki:

Dual-channel architecture DDR/DDR2 SDRAM describes a motherboard technology that effectively doubles data through output from RAM to the memory controller. Dual channel-enabled memory controllers utilize two 64-bit data channels, resulting in a total bandwidth of 128-bits, to move data from RAM to the CPU.

In order to achieve this, the DDR/DDR2 SDRAM memory modules must be installed into matching banks, which are usually color coded on the motherboard. It is not required that identical modules be used, but it is often recommended. It is possible to use a single-sided module of 512 MiB and a double-sided module of 512 MiB in Dual-channel configuration but how fast and stable it is depends on the memory controller.

To clarify: if your motherboard has, say, two pairs of different coloured DIMM sockets (the colours indicate which bank they belong to, Bank 0 or Bank 1) then you can place a matched pair of memory modules in Bank 0, but a different capacity pair of modules in Bank 1, as long as they are of the same speed (and, ideally, manufacturer). So a pair of 1 GiB memory modules in Bank 0, and a pair of matched 512 MiB modules in Bank 1 would be acceptable for Dual-channel operation. This is described in some detail in the Kingston Technology paper http://www.kingston.com/newtech/MKF_...whitepaper.pdf .

So you can alway uses Dual-Channel RAM, but you might not be able to run it in Dual-Channel mode if your motherboard doesnt support it.

[looqas]

You already have 2 sticks so your only hope of making your computer to function in dual channel mode (permitting if your mobo supports the whole feature) is to get 2 x 512 MB sticks with the same latencies you are having now in your comp.

I tried to google the mobo and it gives that you are using Dell/HP or other OEM ready made setup. If this the case then open up the case and check that you have indeed empty slots for extra memory. These ready made packages are quite notorious for cutting costs by including only one IDE and two memory slots. If you do have two extra slots then get cpuz and check the latencies under the SPD tab. And then look for 2x512MB PC4200 (DDR2 533MHz) packages that have the same latencies e.g. 4-4-4-12 that you have in your setup.

Or you can roll a bit of dice and get DDR2 800Mhz memory to pair with your 533Mhz. The 800Mhz will reduce itself's speed to match those 533Mhz you have.

But I wouldn't really bet on it with your mobo and it's proprietary BIOS.