I have a couple of observations running dual 5870s on an I7:

I was getting low GPU loading (44%) until I turned off all CPU crunching. The load immediately went to 99% on both cards. 2 wu are using 25% of the processor which in itself isn't a problem but different than the old DNETC.

The temperature on the cards at 99% loading is FAR below what the old app ran. In fact the temps are as cool as Collatz which uses only SP math. They run much cooler than MW at the same load.

In the old version both GPUs would crunch simultaneously until it got to the end of the computation and if there was 1 remaining packet then 1 GPU dropped out until completion. On this one both GPUs run for a period and then they seem to start alternating with one sitting idle.

In the old app occaisonally one GPU would drop out for some reason and the run times were quite a bit higher than normal. When this happened the CPU time skyrocketed. I'm seeing CPU times that equal my completion times ie 2200s.