AM2 Memory compatibility?

The M2N-SLI supports DDR2-800 RAM just fine. The only problem would be OCZ DDR2 RAM and AM2 boards. They don't play nice together.

Here is a good explanation of it all:
http://www.anandtech.com/cpuchipse [...] =2762&p=10

You can put DDR2-800 in any AM2 motherboard, however, don't assume that using DDR2-800 will result in memory clocked at 800 MHz, this would be incorrect in certain situations.

And those situations would be where your CPU and RAM frequencies aren't evenly divisible by 400. I don't know if that's going to get fixed in the future, or if "that's the way it is."

As far as memory compatability goes, some AM2 boards don't play nice with non-Micron IMC's (integrated memory controller). OCZ uses one, as do many budget ram makers. Asus is known to have this issue, though I've read on OCZ's support forum that the most recent BIOS (0203) fixes this error, at least for the M2N-SLI.

X2's are the only ones that support DDR2-800. Single core CPUs only go to 667. I'm assuming that's because you just don't need the bandwidth with just one core, but its hard built into the CPUs. So the fastest ram you really NEED to buy is 667, since even trying to run 800 on a single core is going to clock it down to 667.

That said, 800 clocked down to 667 can get some pretty damn good timings. I checked CPU-Z on mine and it says my CAS5 DDR2 could run at CAS4 at 533, and this is corsair's budget ram. So if you bought mid-grade 800 and clocked it down, odds are you could really tighten the timings.

Unless you are keen on spending well over 200 on 2 gigs of ram, 4-4-4-12 is the best you're going to get. And even that is borderline, you can find it right now with rebates for 150ish but you'll have to pay close to 200 up front.