I didn’t measure the resistances of the additional resistors with which I achieved the necessary result because the dividers may have different initial resistances on cards from different manufacturers or even from two lots by the same manufacturer. The ratio of resistances is more important here than their absolute values.
The following table shows the initial and final voltages of the VPU and memory. Again, these are the minimal voltages at which the graphics card remained stable at its regular frequencies.
Nominal Voltage, V
Reduced Voltage, V
As a result, we have the VPU voltage reduced by 15% and the voltages of the internal circuitry and the I/O buffers of the graphics memory reduced by 26% and 15%, respectively.
This is what the graphics card looked like during the tests:
The graphics processor and memory immediately reacted to my modding by becoming cooler:
We’ve got excellent results: the temperatures of the graphics processor and memory went down by 4-5°C in the Idle mode and by 8-10°C in the Burn mode.
By limiting the power ration of the fan we nearly halved its speed, from 4020rpm to 2410rpm. The card got silent, producing a kind of soft whisper. The tradeoff was quite acceptable: the card was 3-4°C warmer in the Idle mode and 4-5°C warmer in the Burn mode.
So we’ve reached our goal: by reducing the voltage we made our RADEON 9700-based graphics card both: quieter and cooler.