Don’t have an answer, just that I’m seeing the same effect having just upgraded system from P4 2.8 GHz HT (which maxed to 100% on “both” CPUs during render) to Q6600 @ 3.0 GHz which drives all 4 to about 50% during renders. Overall the Quad is about 6 to 8 times as fast as the older one… just wondering what could be done to drive it harder!