I'm working on an APU build atm, and I was never fully clear about RAM voltages. The motherboard I plan to buy has this listed on the website:
4 x 1.5V DDR3 DIMM sockets supporting up to 64 GB of system memory
* Due to a Windows 32-bit operating system limitation, when more than 4 GB of physical memory is installed, the actual memory size displayed will be less than the size of the physical memory installed.
* The maximum 64 GB of system memory can be supported using 16 GB (or above) memory modules. GIGABYTE will update the memory support list on the official website when the memory modules are available on the market.
Dual channel memory architecture
Support for DDR3 2400(OC)/2133/1866/1600/1333 MHz memory modules
Support for AMD Memory Profile (AMP)/Extreme Memory Profile (XMP) memory modules
(Please refer "Memory Support List" for more information.)
So, this means that when I'm picking RAM, I shouldn't be picking anything higher than 1.5V, correct? I ask because I was looking at 2133 MHz RAM for the build, but everything with 1.5V was a little bit more than I wanted to spend.
Also, I wanted to ask about 'Memory Support Lists' that the manufacturer compiles. These aren't all-inclusive, right? I was planning to use some G.Skill Ripjaws X Series RAM in the build, but it isn't explicitly listed (it's kind of a short list).
Getting the ram to work at 2133 MHz is much easier with a bit more voltage. That's why the manufacturer uses 1.65v instead of 1.5v. If the mobo only supports 1.5v (what I doubt), you are limited to that. And you are right for the Memory Support List. It includes a limited number of tested modules.