How to build a NAS box

Intel Core i3/i5

If you are using an Intel Core i3, i5 or G6950 CPU then here's our recommended BIOS settings for underclocking them in a Gigabyte H55 motherboard. Obviously, different CPUs will require slightly different voltages to run stably.


We were able to underclock the Core i5-661 CPU to 2GHz and run it at just 1V, with its integrated graphics and memory controller (that are both contained on a separate die to the CPU cores) running at lower 500MHz at 1.2V, down from 1.35V. Finally, we dropped the memory voltage to its lowest 1.3V value and underclocked the QPI frequency slightly as well.

AMD Athlon II X2

Our prefered choice of CPU for a NAS box is an Athlon II X2 or Sempron. Here's our BIOS settings in a Gigabyte 880G motherboard.


We downclocked our Athlon II X2 255 to just 2GHz with a 1.6GHz Northbridge and HyperTransport clock and left the memory to use its SPD settings at 1,066MHz.

This allowed us to reduce the voltages quite a bit - some to their minimum levels. Notably we managed to get the CPU down to 1.15V and the 880G chipset all the way down to 0.9V with its core clocked back to just 300MHz since it won't be doing anything strenuous.


We also disabled most of the onboard peripherals too since they won't be needed. The SATA controller was set to ACHI mode once we had the system booting from its USB stick.