A64/Registered memory - what's the story?

[headless]

Could anyone clarify exactly what the situation is with A64 and registered DIMM's? I have a 512mb of corsair LL 2-2-2-5 333mhz RAM here that i want to drop into an upgraded box. I'm looking at moving from my 2500+ (1.83ghz Barton) up to a 3000+ or so A64. I've looked at the FAQ and done some searches and it appears that registered dimms are not required on the new 939 motherboards -- my question is, are they required on socket 754 mobo's? Some of them/all of them?

 

[Wrench00]

Only socket 940 User registered ie FX chips and Opterons. A64's DON'T use registered memory