Funziona con Sapphire e XFX per certo.

Sapphire have done their own PCB for non reference 5870 card which is called Vapor-X. This mod is for rev.2 cards with blue PCB.

There is no possibility to adjust voltages with software, but I don't find this annoying as long as clocks are good.

Here is VGPU, OCP and Vmem mod. (Vmem mod is not tested yet, but it should be correct 100%) Reading points can be found from same picture.

*OCP mod: Tune recistance down to 5Kohm. (9.9Kohm originally) It should be ok up to 1.5V
** Effect: More current can be drawn to GPU
*Vgpu mod: Slowly tune down recistance. On 2D 1.17V is 1.41V in 3D. Those are the settings I use with aircooling
** Effect: More MHz for GPU. Better cooling will give better results.
*Memory Vmod: Tune recistance down slowly. Measure from the leg of coil.
** Effect: May help memory overclocking when using LN2 as a cooling method. May also help with cold tolerance.

Here is memory controller mod. Reading point is on the back side of the card. (Leg of coil)

*Memory controller mod: Tune recistance down slowly. Stock voltage is 1.25V in 3D load. Use the values you prefer.
** Effect: May help memory overclocking when MHz are high. May also be needed while using LN2 as a cooling method.

Here is VPCI-E mod. This is unconfirmed yet, so do not try if you are not sure by yourself.

*VPCI-E mod: Tune recistance down slowly and measure from SMD recistors on the back of the card.
** Effect: May help cold tolerance and overclockability while using extreme cooling methods.

Mod by SF3D
Sapphire 5870 Vapor-X (non reference) Vmods - XtremeSystems Forums