The interest for graphic cards’ voltage control appears when people wish to get better overclocking results. Fermi cards, based on GPU GF100 , with its high temperature make you think twice, especially if you are considering to keep the stock cooling system. However, we will try to manage voltages for other purposes — we will change voltages for different operation modes in order to reduce temperatures and noise level.
We checked conformity of software monitoring data and multimeter measurements and put it into the following table:
|GPU Voltage (monitoring)||GPU Voltage (measurement)||GPU Voltage (monitoring)||GPU Voltage (measurement)|
If you set voltage value lower than 0.800V using software it won’t happen in reality. 1.087 V limit can be extended by BIOS editing, but this time we won’t need it.
Lets use our knowledge about graphic card’s voltage to reduce GPU’s temperature in idle mode (Desktop mode) and when watching a movie (Blu-Ray Playback mode).
At the time this article was written there had been no support for voltage control for Desktop and Blu-Ray Playback modes, therefore, we will do it with the help of BIOS editor NiBiTor and try to lower the voltages for the modes specified:
Using nvFlash tool we flashed the card with modified bios. For this you need to put the BIOS file in the same folder with the tool.
New Bios is flashed using the following command:
nvflash -4 -5 -6 name.rom
here name.rom — BIOS file name.
Before flashing new BIOS it is necessary to save the original using the following command:
nvflash –save original.rom
Those of you who can’t dare to modify BIOS yourself, here is our variant of GTX 465 BIOS with lowered voltage.
Those of you who are brave to modify BIOS yourself, there a couple of important tips that were discovered during our researches.
The editor can set voltage lower than 0.637 V:
Flashing the card with modified BIOS which had these voltage setting led to the opposite — card’s voltage in idle mode instead of set value of 0.6125 V increased to 1.484 V:
So called OCP (overvoltage current protection) safety feature saved the card from malfunctioning, it does not allow increase voltage on GTX 465 and GTX 470 cards higher than 1.225 V. Despite the software monitor readings the measurement using multimeter confirmed the GPU having 1.225V set.
We continue our experiment on reducing the voltages for Desktop and Blu-Ray Playback modes and tried to lower the voltage for 3D mode. There is no need in special BIOS editing software this time — using one of the following software MSI Afterburner or NVIDIA Inspector we can change 3D mode voltage the software way. Quite a long gaming test of the card revealed the full stability of our GTX 465 sample at 0.862V:
After flashing the card with modified BIOS and lowering voltage for 3D mode we finally collected the following results of GPU work:
|Core Clock||Memory Clock||GPU Voltage (custom)||GPU temperatures at 25°С (custom)||Fan speed (custom)|
|Blu-Ray Playback||405 MHz||162 MHz||0.812||48°С||40% (1430RPM)|
|3D Load||607 MHz||800 MHz||0.862||86°С||61% (2540RPM)|
Despite a small voltage change, we couldn’t find any errors found in operation of our PoV GTX 465 sample.
Minor temperature improvements of our sample made it easier for card to operate at 30-degree summer heat.