I have just come across a strange anomaly on my system. First my setup is as follows I7 920 @ 3.6ghz, 12gb of triple channel ddr3, 2 x GTX460 with moderate overclock and 850w power supply. Now usually I run 4 CPU work units and 4 cuda work units (2 per GPU), giving  a total of 8 units in process at any one time. Now as my I7 has hyperthreading I upped my CPU usage to 6 work units and within two minutes I noticed my GPU temperatures starting to drop.  It would appear that my 2 GPU's are now taking 20% to 30% slower.  If I reduce the CPU back to 4 units the GPU's return to normal temperatures and throughput.

Any thoughts ?

CPU utilization is only showing as 70% whilst the processing the 6 CPU WU and 4 GPU WU and yet something is holding the GPU back.

CPU useage increases to 100% momentarily when new units are fed to the GPU after one has completed.

Boinc Version 6.12.14 (X64) Beta  seem to go some way to easing this problem and so far seems stable.