Confused as to which memory module I need...

[darren_uk]

I really haven't a clue what memory module to get:


Motherboard: ECS 945GZT-M v1.0

Online manual says:
"MEMORY
Dual-channel DDR2 memory architecture
2 x 240-pin DDR DIMM socket support up to 2 GB
Support DDR2 533/400 DDR SDRAM"

Also on the website it says:
"Dual channel DDR2 533 memory delivers up to 8.5 GB/s for more responsive system performance."



BUT here's my confusion:

I looked at the table on
http://en.wikipedia.org/wiki/DDR2_SDRAM


So I don't know whether to get a DDR2-533 that runs at 100MHz,

Or a DDR2-1066 that runs at 533MHz.

Also, the DDR2-1066 has a throughput of up to 8.5Gb/s so it seems that it's the DDR2-1066 that I want, but I'm just put off by the "DDR2-533" label.

[jlreich]

Your confusion is from looking at the true bus speed. DDR means Double Data Rate. Simply speaking data is being transfered twice during a single clock. So while a bus speed of 266=533 (roughly), also 533=1066. The bold speeds are what we call the "effective speed" and is how the ram is named.

You want DDR2-533.

If in doubt go to Newegg's memory section or one of the major memory manufacturers and use their lookup tool to input your make/model and it will give you a list of compatible memory.

[darren_uk]

Thanks jlreich.

The thing that threw me was the claim on ECS's website that they support DDR2-533 which "delivers up to 8.5 GB/s for more responsive system performance"

On the Wikipedia page I quoted, only the DDR2-1066 delivers up to this throughput. The DDR2-533 does not come anywhere near this.

Your thoughts?

(I'll also go off and look at the sites you suggested - good pointer, thank you again)

[jlreich]

Well, they are both correct. If you run DDR2-533 in dual channel mode it can theoretically have a bandwidth of 8.5MB/s. Dual channel is a way to use ram in pairs to potentially double the bandwidth. Which is standard and what you want to do and is why ram is often sold in pairs these days. It just depends on how one place lists it. Some will list the single channel specs and some will list dual channel. So looking at the Wikipedia list you are looking at single channel specs. So you can also double the bandwidth for 1066 as well for running in dual channel mode.

Again we are talking about effective speeds. Ram specs can be confusing, but once you get the hang of it it is fairly simple.

Here is one for you. Look at my signature, see the 4000 for the memory on the video card. The actual clock speed is 1000MHz (or 1GHz), but the effective speed is 4000MHz (or 4GHz). : p I could accurately list it as 1000 or 4000. But 4000 is more impressive. ;)

Once you begin to understand how clocks and buses work in relation to each other that Wikipedia chart pretty much lays it out for you. But, as this has caused you confusion, unless you do understand the differences you can't compare two different charts that list things differently. Particularly confusing is how the clock and bus speeds tend to overlap each other as speeds progress faster and faster.

You need DDR2-533. ;)

[darren_uk]

Thanks once again jlreich :)

I did put new memory modules in - sadly, it didn't solve the problem.

I'm about to write a new thread....