Setting GPU core voltage on GTX280

What I really need is a software method to adjust the GPU core voltage on my Gigabyte GTX260 (GV-N26OC-896H). I recently upgraded from everest Ultimate 4.50 to 4.60 because it had a GPU fan speed monitor for the GTX280.

About Every 4-5 hours Riva Tuner (both 2.10 and 2.20) allow the GPU fan speed to change from "fixed 100%" to "auto 25%. this didnt used to happen on the Everest 4.50 version...but 4.50 didnt show my GPU fan speed either.+

Gigabyte GA-P35-DS3P
Intel E8400 + Thermalright Ultra-120 eXtreme
GTX280
Cooler Master HAF932
Antec Neopower 650W PSU

Thank you

change the voltages and fan speed to an absolute stable value of 0.85V for 2D mode at 300MHz with the 3D mode at 0.95V running at 400MHz and the Extra mode at 1.075V. On idle the fans rotates at 915rpm, absolut silent 28% and the GPU temp stays at 43°C. After 20 minutes Furmark the temp went to 70°C and the fan turns at audible 2614rpm or also 79%. I personally prefer less temperature over less noise. Thanks to NiBiTor you can change this in an easy way.

Use EVGAs voltage tool. Note that it does not work on 55nM cards. This is the tool but you cannot download it from EVGA unless you have a registered EVGA card that can use it.

There is a possibility that your card uses a different programmable voltage regulator. If this is the case, you may have to use the manufacturers tools.
Note that if you have a 55nM card, unless it is a custom model, you will not be able to use a tool to change the voltage.

Are you running Everest AND RivaTuner at the same time? If so, try running Everest only. The two programs could be conflicting with each other. Also, I have one suggestion based on the equipment you have listed. The heatsink you are using should be replaced with the AM2 version of the 9500. The 9500AT was designed for Intel ships (which are slightly concave on top) and is not perfectly flat on all axis. I discovered this domed plate for heatsink when I changed from the copper 9500 to the AM2 nickle plated. The difference is cooling is significant. But to be honest, pick up the sunbeam core-contact freezer. Costs less, cools waybetter.

Again. Just a suggestion, if anything it is something for you to ponder.

You can modify the bios to use a higher voltage (if it isnt already at the maximum voltage) but the range is extremely limited. The highest voltage you can use is that used for the high overclocked cards like the EVGA SSC version. There is no going beyond that voltage unless you work out a hardware mod.