My PC has the fans controlled by Speedfan to maintain the CPU temp under 80°C. Trouble is it's been tending to crash occasionally on me...
PC spends a lot of it's time running Folding@home on the CPU and GPU, i.e. 100% load on both. Not as bad as Prime 95 + Furmark but not far off.
Yesterday I noticed that Speedfan wasn't changing the figures and found it was non-responsive so I killed it and loaded it again.
Now my PC runs around 300w AC under folding load and Speedfan is set to run fans at 25% idle and up to 75°C CPU temp, 75~80°C is 50% fan speed and 100% over 80°C.
It tends to cycle between the 25 and 50% settings but isn't particularly noticeable or annoying, most of the time, in it's doing so. I think it had set the fan 25% and then crashed so didn't raise them as needed. As I'm crazy I've attempted to recreate the situation for you viewing pleasure!
In fact I think I caught a glance of one of the CPU cores at 99°C, which would be throttling temperature! PC hadn't crashed though nor was it acting up and doesn't seem I've done any harm.
In the above shot I don't think the CPU was even throttling, the PSU fan is way above normal due to extreme heat under it cooking it's casing and the hot air it would have been tending to draw in.
Speedfan, once working, shoved the fans to 100% and fairly quickly brought the temps back under control.
I've now updated Speedfan and will keep an eye on it.