I have 270X's in Crossfire OC'd to 1150 core and 1500 mem on a Sabertooth 990FX board with an FX8320 OC'd to 4.2ghz and 16gb (4x4) CAS9 1333mhz memory.
My question is: when running Unigine Heaven 4.0 and using Afterburner to monitor temps, gpu utilization, and clocks it shows GPU1 at 100% utilization while GPU2 is peaking at about 85% utilization. Is this normal, an indication of bottlenecking, or too high an OC?
My 8320 passed the standard Intel Burn Test so I know the CPU is stable.
Depends a little on crossfire optimizations and the game or bench, but I have seen it before. Some games will use both to 100%, others will use the primary a bit more. Remember that the primary also has the task of compositing data from both cards into the single output frame to your monitor, so there's a little bit of overhead there as well.
Side note: Consider upgrading to DDR3 1866 RAM for that system, or see if your 1333 can be OC'd to 1600. Just a suggestion.