F3-10666CL7D-8GBXH vs MV-3V4G3

Solution
The Samsung memory will work at 1.50 V. And this memory is low profile, which means it is smaller in height compared to most other memory, so it should fit in the motherboard with no problem.

But note that the G.Skill memory is faster performing than the Samsung memory. So if you want maximum performance, then the G.Skill memory would be the best choice. But the G.Skill memory is a bit taller in height compared to some other memory, so it may not fit in a motherboard if using certain CPU coolers that sit lower down towards the motherboard.
The G.Skill DDR3 memory F3-10666CL7D-8GBXH is rated at 1333 MHz @ CAS Latency 7 @ 1.5 V.

The Samsung DDR3 memory MV-3V4G3(D) is rated at 1600 MHz @ CAS Latency 11 @ 1.35 V; and at 1333 MHz @ CAS Latency 9 @ 1.35 V.

For operation at 1333 MHz, the G.Skill memory has a lower effective latency, so is faster than the Samsung memory.

But the Samsung memory can run at a lower voltage of 1.35 V, compared to the higher voltage (1.5 V) of the G.Skill memory.

The Gigabyte GA-990XA-UD3 Rev3.1 motherboard, I think, only supports memory voltages from 1.5 V and up. So the Samsung memory can't be run at 1.35 V, but the Samsung memory can be run at 1.50 V instead.
 
The Samsung memory will work at 1.50 V. And this memory is low profile, which means it is smaller in height compared to most other memory, so it should fit in the motherboard with no problem.

But note that the G.Skill memory is faster performing than the Samsung memory. So if you want maximum performance, then the G.Skill memory would be the best choice. But the G.Skill memory is a bit taller in height compared to some other memory, so it may not fit in a motherboard if using certain CPU coolers that sit lower down towards the motherboard.
 
Solution