Re: Always registered.
20 years working in IT, and I've never had to match a RAM and motherboard and CPU socket combination. If you want to play silly marketing games, then someone else can mess about and guarantee compatibility for me, and I'll back it to them if not.
Set a standard, sell me a chip. Because the only thing I ever upgrade on a PC is the RAM anyway, and usually by slotting more in, rather than replacing what's there.
Last time I knew / understood the naming allocations of things like that, I was looking at adding 2MB to a 386... and then it turned out that we had SIP chip sockets for main RAM and not SIMMs on the motherboard (I kid you not... the only other place I've seen SIP's, mainstream-PC-wise, was in a Laserjet 4).
To be honest, I actually laugh when people tell me that they "built" their PC nowadays. What they mean is they bought a kit of already-compatible parts and plugged them together using the modern equivalent of ZIF sockets, and ended up with a machine that's no cheaper and no higher-performing than if they'd just bought a decent PC as a unit. Oh, unless you count that LED junk that slather everything with. No word of a lie, last time I selected a RAM chip for my personal use, I had to exclude those with RGB LEDs on them... I mean... WHY?!
P.S. Those two memory "features" sound bog-useless unless you're clearing RAM, and I can't imagine that you do that often enough to warrant specific support for that, presumably in the motherboard and the OS. If you do, it's after you're done with something, so who cares if it takes a few microseconds to finally release the RAM after clearing it?