Recent power management discussions plugged into one of our current frustrations, namely the interaction of the screen lock and power-save features on Intel/CentOS 6 platforms. We certainly would not have guessed that locking the screen would inhibit going into the power-save mode, but it sure seems to do exactly that on some of our test platforms.
If one leaves the desktop idle for the timeout period, the computer sleeps. If one locks the screen and then leaves the machine idle, the computer does not sleep. We were hoping that this "feature" was isolated to just our older Dell desktop machine hardware and firmware, but it appears elsewhere as well.
Possibly more interesting is that most of our systems were loaded with CentOS 6.X almost two years ago and have been updated at least weekly ever since. This new power-save scenario has appeared just within the last three weeks,and our investigations have not discovered the cause ora solution.