Sapphire HD5850 Xtreme / HD6850 Volt-Mods (vGPU & vMEM)overview
The PCB is identical to those of HD6850s with AMD reference design. This means these mods can be used for HD6850 as well
A 4-phase switching regulator, which is located between the GPU and output panel, controls the GPU voltage. For the memory a simple single phase switching reg is beeing used.voltage measurement
output caps of both switching regs are always a good spot for voltage readings. though the little MLCC at the back of VRAM ICs and GPU will give you a more accurate reading.
If u are using software like Trixx to adjust vGPU be aware that those values are different to the real voltage. Here's a table with exact measurement:
IC: CHiL 8214
FP Pin: Pin 4 (VSEN)
original resistance: 12.4 Ohms
recommended VR size: 500 Ohms
*Masse = ground
*put a 500 Ohm VR between FB Pin and GNDvMEM mod
FP Pin: Pin 6
original resistance: 5010 Ohms
recommended VR size: 200k Ohms
Pin 3 is a good ground spot. A pencil mod is possible alternativelyoverclocking
I did some tests with the integrated benchmark of Crysis. Tested in 1920x1080px, DX10 very high details, HQ 16:1 AF and no anti aliasing.
Max. clocks at default voltages are 850MHz(GPU)/1300MHz(VRAM). With an increased GPU voltage of 1.29V(real) and 1.66V VRAM voltage it runs completely stable and without any artifacts at 970/1340MHz. For now I didn't tested more volts because of the stock cooler and high ambient temps.
Benchmarks will run with more than 1000MHz GPU clock.