I would tend to be disappointed if during a render 100% wasn't being used. To take Scarab's example if you were running a 2.8GHz machine @ 50% you'd be doing just as well to run 100% on a 1.4. There'd be no point in upgrading. I've upgraded my machine a couple of times in the last year and amazed at how linear the improvements are. I have a scene saved as a testbed and the relationship between processor and rendertime is exact. (Have been using the same O.S.-Win2K througout all upgrades.) To further address visque's concerns I would say that if processor usage remains at 100% when it is NOT rendering I would be asking questions... (setting up a scene and such) If your system is doing no work, not moving anything etc. you should see that reflected.