DDR transfers data twice as fast as its sdram counterpart.
If your going to get a ddr mobo and ddr sdram, you want to get pc2400 or pc2700 ddr sticks just to kind of future proof your ram. It doesn't cost very much more, if at all.
There are only two motherboards (Asus A7A266 & ECS K7S5A) that can use either SDRAM or DDR-SDRAM. All other motherboards use one or the other. You need to find out which your motherboard uses and get that.
well, you need a motherboard that will support a DDR RAM.
In general, DDR is twice as fast as SDRAM although it is a kind of SDRAM.
Actually, SDR is not Single Data Rate as Double Data Rate is (although technically it is) but Synchronous Dynamic Random Access Memory. DDR could be called as DDR-SDRAM more correctly.
Both cost almost as much so you could go for a DDR memory based board. Currently there are no DDR based Intel chipset boards available for intel processors, but you can get VIA Pro266/T, ALi chipsets and new SiS chipsets that use DDR for P3. DDR is now a de-facto platform for AMD chips.
In any case you could be better off with DDR RAM whatever your application.
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