On CentOS 6.6, I find that it can make the screen (console, not X) blank after a while. However, it does not power the screen off.
This usually work on Fedora or other releases. I guess this is caused by some configurations specific in CentOS 6.6.
How to make CentOS 6.6 power off the console screen automatically?
You may try removing the
nomodeset. It plays the trick for me.
For some general information, please check: