WMI class does have the
property that at least supports DDR-2 (might be updated as of late). See http://msdn.microsoft.com/en-us/library/aa394347(VS.85).aspx
]. Are you not seeing this? I do see it on my Win7 box.
CPU temperature is reported differently for different motherboard manufacturers. If they haven't implemented a WMI provider for the temperature, you can't get it without a specific driver and ability to access it.
may work for some motherboards, but also only seems to be updated during high temperature events.