Backwards compatibility of RAM

[tgxiii]

I'm a bit confused. I was under the impression that if your motherboard says it only supports up to DDR266 that DDR266 is the fastest RAM you can use. I've been told by other people that you can install DDR400 in a mobo that supports up to DDR266. So, what's true or not?

The mobo in question is the ECS P4VXASD2+. Someone said that you can put in a DDR400 stick in it, but the specs say it only supports DDR266/200.

[Peter M]

A clear Yes here. SDRAM (be it SDR or DDR) has no relevant lower speed limit - so yes, a DDR400 stick runs at lower speeds. The rated speed is actually the MAXIMUM speed, not the one and only speed.