I've been having trouble enabling manual fan speed control on my Asus GTX570 card, so much trouble I decided to drop the recommended strategy for enabling manual fan control and do it my way which of course is always the best way (haha). I removed the card, opened the case, unplugged the fan from the header pins, figured out which pin is + and which is - and connected it to a wall wart type AC adaptor that is rated for 5 volts DC but gives an open circuit voltage of 8.5 volts. I cut a notch in the side of the case for the wires to hang out, put it back in the computer, booted and it works. I expected that the card would notice the fan is no longer connected to the card and refuse to work but it does. That's fortunate because it removes the need to rig a dummy fan just to keep the card happy and thinking it's in control. However it says some rather unpleasant things about thermal protection does it not?

I wasn't able to detach the fan to check if it's rated for 5V or 12V but I figure it's probably running at ~7V. From the sound level I would say it's running at above the 85% I had it running at earlier. The temperature is below what it usually is but that might be because I'm getting beta test tasks right now which are reported to not run the GPU very hard.

Tomorrow I will get a wee torx driver so I can unmount the fan and check it's voltage rating. I may connect it to the 12V from the main power supply.

If anybody's wondering why I bother with manual control when I have my excellent "cooler cabinet" it's because if I leave the thing on auto fan control it reduces the fan speed to 40% and allows the GPU to run at 80 to 85 Celsius which is not acceptable.

Anyway, I am no longer interested in making Coolbits 4 work. I will hack the card and connect the fan to my own controller so that I will have manual control even without Coolbits 4.

Hi nenym,

I am almost done. I have proven the concept works, at least it works on my Asus 570. It might not work on other brands or models without adding a dummy fan but that should be easy. The only thing left to do is figure out how much voltage I should feed to the fan. After I purchase the torx screwdriver required to remove the fan from the card's chassis I should be able to find a part number I can lookup to find out if it's a 12V fan or a 5V. The voltage rating might even be stencilled on the fan itself.

After that I will try to hack the BIOS to allow easier voltage and clock tweaking. Then it will either become a brick or become the card it should have been when I bought it. When people ask me, "Is that thing new?" I often tell them, "No, it's better than new, I already fixed it."

Ok, I got the proper torx bit, a T6, and dismantled the card (Asus GTX-570). There was dirt EVERYWHERE inside except in the heatsink fins in spite of the fact I've been blowing it out every few months. I'll be dismantling that card every few months now for a proper cleaning as I now see there are just too many nooks and crannies inside where the dirt can collect and not get pushed out by compressed air. There were probably 10 ICs that were completely buried in dirt and I bet they were overheating. I'm very glad I dismantled it.

Anyway it turns out the fan is indeed a 12V fan so I wired it to 12V on one of the disk power connectors and now that fan runs at 100% with no Coolbits option in xorg.conf. It's crunching a PrimeGrid task for a test because they seem to work the GPU harder that the GPUgrid beta tasks I've been getting. Ambient air temp is 10C and the GPU temp is 35C.... perfect!

Now if I can hack the BIOS I should be able to OC and OV the snot out of it and make it crunch as fast as a stock 660ti ;-)

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