Make sure keyboard is plugged into the computer.
1. Let the good old Asus splash screen go through.
2. Hit delete when the screen goes away and it says "Press any key..."
3. Scroll over to the Boot tab.
4. Go to Boot Device Priority
5. Change 1st Boot Device to your CD/DVD Rom Device. (You will have to find it in the list, just hit Enter).
6. Save and Exit.
7. Pop in your OS CD before the system reboots.
Now it will load the disc and just follow installation instructions. Let me know if you run into problems, I have the same mobo as you do.