Run Queue Thresholds

Gurus,
Having a GS1280 box with OSF1 v5.1 installed (16 processors), the run queue value from the vmstat command reports a very high value (about 25 to 30). Does this reflect a CPU bound system. Note that the average CPU utilization is about 60 % which means that the CPU is not that loaded.

Can anyone advice about the threshold of the run queue value on Tru64 ?