Real CPU Usage vs. Pro Tools System Usage Window

[tbonesteak4dinner]

Hello everyone,

I have a question regarding how Pro Tools 11 calculates system usage. I'm working on a fairly heavy project. My system hardly slows down for anything so when it choked during a couple sections I broke out the diagnostic tools.

HWinfo64, CPU-Z, CoreTemp, etc. all show CPU usage as peaking at 55% at the heaviest part of the project, otherwise it stays in the mid 30% range. The Pro Tools system usage window shows sustained CPU usage of over 100% (bar turns red) during the heaviest part, and otherwise will hang around 50-70%. In addition, I confirmed there is zero thermal throttling going on.

I'm pretty confident in my build and have run it through the whole gamut of Prime95, IBT, and other tests and I've seen it get stressed to its limits. WIth this project, it's just getting to the point where the processor should begin to work, yet Pro Tools seems to think it's hitting its limits and is acting accordingly.

First thing I could point to, and maybe something I don't entirely grasp, is my interface's impact. I'm using an old 003 rack and believe me it's first on the list to upgrade. Is this my bottleneck or did I miss a fairly rudimentary setting somewhere?

Thank you very much in advance for any insight!

Relevant Specs:
Core i7-3820 (Overclocked to 4.625Ghz, stable)
16GB 1333 DDR 3 Memory
Separate SSDs for OS, Samples
Separate HDDs for PT Projects, Storage, etc.
Digidesign 003 Rack (firewire 400, legacy drivers as recommended)
Pro Tools 11