I'm converting some HD videos and the average core temprature across all cores on my 2600K is 74 degrees C with all cores at 100% usage.
Is this an OK temprature and will running the CPU at this temprature for extended periods of time (2-4 Hours) have any degrading or detrimental effect on the CPU?
I7-2600K stock clock
Stock intel cooler
Gigabyte P67 motherboard (factory settings)
First, from what I've heard Intel's stock cooler isn't hat good. Replace it. Those are high temps but I think i7 will handle 80C. Maybe some who have it can tell you max values.
But get a new cooler.