CPU-Minutes is a feature introduced in Qube! 6.5, which tracks a job's "cumulative time." This is displayed in the Job Properties tab of WranglerView and ArtistView as "CPU-Minutes", and is stored internally in CPU-seconds.
For example, if a job instance or frame runs for 60 seconds, and has been allocated 3 slots, the "timecumulative" value is set to 180 when the instance or frame is complete/failed/killed. If the same job or instance is retried and is allocated 8 slots the next time around, and runs for 30 seconds, the "cumulative time" is increased by (8 * 30) = 240 CPU-seconds, for a new value of 180 + 240 = 420 CPU-seconds.
We feel that CPU-Minutes is a much more accurate metric for "How much of the farm did I get?" than trying to track cores or processors.