I have a P4 3.0 with 2×512 GB DDR, several harddrives on a Gigabyte mobo.
The system idles at sub 40 degrees celcius, but can rocket to over 60 when rendering video etc. I have an additional large fan stuck on the side of the case which blows in over the CPU/RAM, which I switch on during these intensive operations.
How hot is too hot?