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I've forgotten!!

Sorry thats a query is about memory, i currently have 1 stick of memory in my machine - Kingston 256mb 333Mhz DDR PC2700 - What i'm confused about is the 333mhz and the PC2700 parts, i'm looking for more memory but i'm not sure if i need to buy the same i.e PC2700 and 333mhz, can i mix and match? for instance the one i'm looking at is 512mb 400Mhz PC3200, will this have any effect.

Rnning: P4 2.4Gb and XP Pro.


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It is 99.99% certain

that the PC 3200 [DDR400] will run fine. HOWEVER, with the mix it will only run at the same speed as the other stick. Your memory bus is running at 166 MHz [333 when double clocked].

IF your mobo supports the 400 MHz memory bus speed [actually it's shown as 200, the DDR doubles it] and you use only the PC3200 stick, it should run at the full 200/400 speed.

Get the PC3200, that way if you upgrade you while have the faster memory for the new machine [although the new machine would likely use DDR2 LOL]

The only other possibility, which is not too likely, is that the mobo limits the memory capacity that a stick can have in a given memory slot. There was a time when they couldn't take more than 256 MB sticks.

Some would take 512s in the first two slots, but only 256 in the third slot. Varied widely for a while.

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That's a great help, my board is 533mhz FSB and will take up to ddr 400. I was just a little confused about the PC2700 bit, it seems there are a few different ones.


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Minor point

With memory, the double part of double data rate referrs to the fact that the processor is able to read or write to the memory on both the up and down cycle. Until AMD came along with the Athlon, in the x86 world it was either the up cycle or the down cycle, but not both.

So the FSB speed is really more of an effective speed. Intel took this to a whole new level with their 800MHz FSB, which is really more accurately described as a 2x400MHz FSB. That is, two 400MHz FSB. It's a dual channel memory configuration with two independent 400MHz FSB.

And for pretty much all of this, we have a now defunct company known as Cyrix to thank. Way back when, all FSB speeds were 66MHz, no DDR or anything like that. Cyrix came along and pioneered the 75MHz FSB, which would have probably made them the next Intel if their CPU weren't such a horrible performer, even with the 75MHz FSB. Via owns what was Cyrix now, and is still actually doing some interesting things with the CPU. They've recently added a MPEG video decoder logic to the CPU, and created versions of some open source media player apps to take advantage of it.

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Please don't mix 800 MHz with

Dual Channel. They are absolutely two different things.

The Intel 800 HHz FSB chipsets run at 800 in either mode, single channel or dual channel.

Dual Channel simply adds an additional 64 bit path to give 128 bit memory.

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