You need to go thru all the BIOS options and disable every bit of equipment that you don't use and need.
Like for instance in mine, I don't own a 1394 based piece of equipment, so from day one I have had that disabled so that it doesn't even clutter the registry. No, comports, no ECP, EPP printer ports etc etc.
I use a Audigy, so no onboard Audio, I use 4 SATA discs so all those are detected and the rest are Not Installed and not Auto Detect.
Boot order contains only the OS Drive as the Primary Boot Option. The rest are all disabled. Boot from LAN , no no, Boot from USB, no no never.
Search for FDDs and all the crap at startup no no.
Check and see the options you can disable in the BIOS. Also make sure that before you shutdown your rig, you don't leave a CD/DVD in the ODD. And when you startup a rig make sure that the Power to external USB HDDs is powered off if they remain connected to the rig all the time.