RAM voltages in the BIOS only have one voltage, and that is usually called one of the following
They're all the same, and what to set it at depends on your memory. Check the listing for it, if it says "1.8v" then set it to that for default speeds. There isn't really a "suitable for" as each memory has differences. My current memory gets set to 1.6v stock by my motherboard being on "auto" but the OCZ website says its rated to 1.95v EVP. (extended voltage protection)
Basically, check your memory, rather than the motherboard. The reason for changing the voltage is because they are tested at this, and usually a higher speed requires more voltage. for DDR3, 1066Mhz is the basic, and so the basic voltage of 1.6 or even lower may be ok. As you get towards the 2000MHz stuff, you'll notice the required voltage goes higher.
My old GeIL PC2-6400C4 Ultra (Orange heat sinks) was rated to work at 1.9v, but it was covered to go up to 2.15v, so thats what i put it at, and had it running at 880MHz, at 4-4-4-12 timings.
Research your boards before you buy them. Generally cheapo boards have issues with voltage/compatibility but anything vaguely enthusiast should take whatever you throw at it. Check the Qualified Vendor List on the motherboard manufacturer's website if you want to be 100% sure.
Core i5/i7 mobos need 1.65v DDR3 RAM or below; more correctly, this is not a motherboard limitation but a CPU limitation - in that the memory controller in the CPU doesn't like more than 1.65v.