SQL Sasquatch explains what “max server memory” does and how it relates to private bytes:
Well, there’s obviously a relationship between private bytes and “total server memory”. The peaks and valleys occur at the same time. But there’s a delta between them, and the delta isn’t constant.
The difference between private bytes and “total server memory” is pretty well confined, too – not varying more than 10 mb in this interval.
Read the whole thing.