OK I just did some testing for you.

AHCI Mode for all.

1. Native Mode Disabled/Enabled x2

Selected First Boot Device CDROM and tested with Native Enabled/Disabled.

Second test First Boot Device P4 Asus and tested with Native Mode Enabled/Disabled

All test board hangs/stalls after Verifying DMI Pool...............................
Making a second line here ............................................

Just so you know, if AHCI or RAID is enabled, the Verifying DMI Pool......................... Line will always be there, but only the one single line.

I believe the issue is caused by the board reading the CD first to see if it's bootable or should be booting from it, when there is no disk in the drive the same happens as it's set to boot from CD so it will still scan the drive and have to wait on it.

Fix is simple, set first Boot device to HDD and second/third set none. Then use F12 to boot from CD, it's much easier this way anyhow.

So you know I was being honest, here's an image showing I do indeed have the same hardware you are using