I have an Athlon 2700+ on an ASUS A7V8X-X motherboard. Out of the blue last night when I restarted my computer (it had been on for a couple hours prior - rebooted from a software install) I received a hardware error telling me to check my bios for information. Upon looking at the hardware monitor it showed my CPU temperature as being 80+ degress C.
I immediately turned it off, and after letting it cool for an hour or so I took off the heatsink and fan, cleaned them with compressed air, made sure there was still the little square of grey stuff under the heatsink ( sorry, don't know the technical names of any of this really ;) ) and then reseated the heatsink and fan. Also did a quick clean of the entire insides of the case with the compressed air while I was in there, including the three case fans ( two blowing in, one blowing out ).
After letting it sit for a bit more, I turned it back on and went straight into the bios to watch the temperature. The motherboard temperature never budged from 33C but the CPU temperature rose about 1.5 degrees every few seconds until I shut it off again at the 70C mark.
The heatsink itself is getting hot. And the fan speeds were fairly constant varying only from 44300rpm to 45000 or so in the bios. There had been some dust between the fan and heatsink but that all got cleaned off.
I'm at a loss as to what my next step should be, and of course there is work to be done that I can't do without my computer!