Asus Z8PH-D12 SE/QDR - Manual (Page 42)

2-24 Chapter 2: Hardware information
3. DDR3 voltage control setting (4-pin LVDDR3_SEL1; LVDDR3_SEL2)
These jumpers allow you to adjust the DIMM voltage. Set to pins 1–2 to
select 1.5V BIOS control, pins 2–3 to select 1.2V Force or 3–4 to select
1.35V Force.