Newer generations of HP Proliant servers (I had this with an ML110 G6) no longer show I/O controller messages directly on screen. Instead, they are masked by a graphical status screen.
Not having these messages also means you won't know when you have to hit that certain key (F8) to get into the RAID controller's configuration BIOS, which can be problematic.
To get out of the graphical status screen and see all the I/O messages, you can hit Space on your keyboard during startup. For me, this usually did not work right away, and I had to hit the key multiple times before it got out of the status screen.
When done correctly, you'll notice the I/O messages and intialisation messages of the RAID controller, along with a "Press F8 to enter setup" message.