DDR2 1066 on AM2+

[afusion]

Hai Guys!

I looked up a mobo that had support for DDR2 1066 RAM, and let's just say I'm not exactly sure what this means: "Due to AMD CPU limitation, DDR2 1066 is supported by AM2+ CPU for one DIMM per channel only."

Just to make this clear as long as my CPU is AM2+ (meaning Phenom) I can use pairs of 1GB or 2GB modules that'll run @ 1066 no probs?

[chconline Veteran]

That's the limitation of the integrated memory controller. You don't really need DDR2-1066, you can always stick with DDR2-800. (Y)

[ieatrocks]

Hai Guys!

I looked up a mobo that had support for DDR2 1066 RAM, and let's just say I'm not exactly sure what this means: "Due to AMD CPU limitation, DDR2 1066 is supported by AM2+ CPU for one DIMM per channel only."

Just to make this clear as long as my CPU is AM2+ (meaning Phenom) I can use pairs of 1GB or 2GB modules that'll run @ 1066 no probs?

What it means is that your motherboard has 4 slots for ram. When you use all 4 slots, your memory controller on your AM2+ chip (all new A64 X2, Phenom x3 and Phenom x4 are all am2+) has to relax the speed and timing to ensure that the two memory chips each have enough time to get out the data before the other chip starts giving data.

So, if you have 2 chips @ 1066 and put both of them into one memory channel (check your motherboard manual) then they will still be sharing the bandwidth available, and will not operate higher than DDR2-800; while the second channel goes unused.

It's a moot point anyways, ddr performance/speed works on a curve, where the latency starting the transfer starts to overwhelm the new higher speeds of the ram chips, this is vastly oversimplified but: ddr533 to 667 is a nice big speed increase, from 667 to 800 is still pretty good, but from 800 up to 1066 is not as noticeable.

Bottom line is buy twice as much ddr800 and that'll be cheaper (maybe) and faster overall than half the ram @ 1066.

[afusion]

Ah righteous

Well I've decided to use 2GB of RAM instead of 4GB, I don't feel it necessary to run a 64bit OS.