My Moms 32 bit system has 4GB of PC3 666 memory two sticks I am going to update here new computer with a new motherboard, now question I have would it be better to keep them sticks and put them in a new motherboards, are there mb that take both DDR2 and DDR3 and does anyone know of any AMD MB that do let me know.
No motherboard can run both DDR2 and DDR3 at the same time. There are a few old motherboards that could take either DDR2 or DDR3 but only one at a time, however no modern motherboard can do this. In fact, no modern motherboard supports DDR2 at all. I also think that only Intel motherboards supported choosing between DDR2 and DDR3, AMD motherboards have been locked into one type for a longer time, with good reason.
Also worth noting is I think you meant PC2 666 memory. 666 memory is usually referred to as 667 because it is closer to 667 than 666 and the superstitious fear of the number.
It is called DDR2-667 because the FSB freq is supposed to be 333.3 MHz. X2 = 666.6MHz and a slight round upward gives you 667.
jale, with the price of DDR3 RAM where it is today, just buy what you need. Don't worry about trying to salvage the old RAM.
All you did was add in the info about the FSB (Which is wrong) and the words "round up" to what I said.
For DDR2-667 333MHz is the input/output clock of the module and the FSB may have a different clock, if there is an FSB on the system. Grab a Sandy Bridge CPU and FSB is completely taken out of the equation. The FSB has no direct correlation to the RAM frequency other than providing an upper limit to the RAM frequencies.
For all DDR RAM the memory the actual clock rate measured in MHz is half of what the we are usually told. DDR2-667 is really running at 333MHz. For each clock cycle there is a top and bottom. Usually only one side of each clock is used, either the top or the bottom for most things. For DDR memory both sides of the clock cycle are used which make something effectively run at double the clock rate without increasing the clock rate. Because they run twice as fast they are called DDR or Double Data Rate. Since DDR tech has a clock rate and all RAM memory in RAM modules is of a specific type called DRAM, DDR technology is of a family of memory called SDRAM. SDRAM means Synchronous Dynamic RAM, synchronous beacuse it has a clock rate. The full names of DDR memories are DDR SDRAM, DDR2 SDRAM, and DDR3 SDRAM.
As for DDR3 pricing, yes it is so cheap that the old RAM isn't worth trying to use. Any motherboard that supports DDR2 is outdated hardware and not really worth buying compared to the more recent hardware.