Have you tried checking the system to see what the temps are? You can install any number of programs that will monitor them. I myself like Speedfan, but there are many others. If anything in it is overheating, then this would explain why it is running so much.
If it is because of overheating, you may need to have it looked at (unless you feel comfortable opening it up yourself). It could need new thermal paste, it could need a whole new fan, it could have the wrong component installed for the device (causing overheating), etc.
First start with the temp testing.