I've had this happen several times now, and I don't know what to make of it.
Completely randomly the fan on my GTX 470 will run full bore at what sounds like 110%. Some times it will do it for half a second, other times it will do it for 5-10 seconds. If I check the fan speed in MSI Afterburner it does NOT report this increase in fan speed, which I find totally mystifying. For example, it'll show that its still running at 70% while the fan ramps up to deafening levels and then goes back down after a few seconds.
When I manually set the fan to 100% it still isn't as loud as when it ramps up on its own, so it seems like its running at at least 110% normal speed.
I've had this happen at the windows desktop and I've had it happen in games. I have no idea what could be causing it because my temperatures are stable and there are no spikes in temperature OR fan speed being reported by MSI Afterburner.
Its extremely irritating because its just SO loud. I'm currently using the 257.15 drivers with the latest version of MSI Afterburner with a custom fan profile. I've turned off speedfan just in case it was causing some sort of conflict, and the problem still occurs. I also do not have any PWM fans in my case, so no other fans should be changing speed. I'm 99% certain that it is the GTX 470's fan that is making all the noise because it has a pretty distinct sound.
I can't find any mention of this issue anywhere online.
I posted this problem here
as well, so there is more information in that thread. Its very strange. I've tried disabling Afterburner, going back to stock voltage and stock clocks, setting the GPU power saving mode to "performance" rather than "adaptive". I have no other hardware monitoring programs or services running. It will happen totally randomly for like half a second, usually when I'm just sitting around browsing the internet, and its so loud that it makes me jump out of my chair. It'd be funny if it wasn't so irritating. ;)
Also, here are my specs (copied from my signature on the other forum). CoolerMaster 690 II Advance - Gigabyte GA-EP45-UD3P - Intel Core 2 Quad Q9550 @ 4.0Ghz + Thermalright Ultra 120 Extreme
6GB DDR2 @ 942Mhz 5-5-5-20 1.9v (2x1Gb Wintec AMPX PC2-8500 & 2x2Gb G.Skill PC2-6400) - EVGA Geforce GTX 470 @ 750/1500/1850 (1.050v)
Sparkle Geforce GTS 250 1Gb Low-Profile (Physx) - Seagate 7200.12 500Gb SATA - Seagate 7200.10 320Gb SATA - Seagate 7200.8 200Gb SATA
ASUS VW266H 25.5" LCD - OCZ GameXStream 700W PSU - ASUS Xonar DX - Logitech Z-5500 5.1 Surround - Windows 7 Professional x64