The CPU Usage Limit setting in the Playback Engine controls the percentage of CPU resources allocated to Pro Tools host processing tasks. Used in combination with the
Host Processors setting, the
CPU Usage Limit setting lets you control the way Pro Tools tasks are carried out by the system.
The maximum available CPU Usage Limit depends on the number of processors in your computer and on the number of processors you specify for host processing. This value can range from 85% for single-processor computers (except for 003, 003 Rack+, 003 Rack, Digi 002, and Digi 002 Rack, which have a limit of 99%), and 99% for multiprocessor computers (which dedicate one entire processor to Pro Tools).
On multiprocessor computers, the maximum CPU Usage Limit is reduced when you use all your processors (as selected in the
Host Processing pop-up menu). For example, on dual-processors, the limit is 90%. On four-processor computers, the limit is 95%.