X-bit Labs released a guide about voltmodding power supplies.
There are two systems components that traditionally undergo volt-modding: mainboard (Vcore, Vdimm, sometimes Vagp, Vdd, Vio, and certain model-specific modifications) and graphics card (Vgpu, Vmem, sometimes Vref, Vddq, OVP). Besides these two, you can also volt-mod the Power Supply Unit (PSU) of your computer. A simple modification allows controlling the basic voltages (3.3v, 5v and 12v) of a majority of existing PSUs.
Few off-the-shelf PSUs offer you such control over the voltages. I could only name certain hi-end units from Antec (like the TrueControl 550), PC Power & Cooling, OCZ Technology and SOYO. However, even such units would only become better from some additional tweaking, as their standard voltage ranges are rather narrow.
The guide can be found here
Power Supply Unit Voltmodding Guide
Posted on Monday, Sep 20 2004 @ 17:59 CEST by Thomas De Maesschalck