I have exactly the same problem except that my bios/aptio has chose to hide the secure boot option when the system is preloaded with windows 8. notebook model number s46cm-wx121h
the specs
http://itfairsg.com/sitex2012/asus-notebooks-s-series-s46cm-wx121h-s46cm-wx046h-price-list-flyer-bro...the following is the bios update patchnote from the official asus singapore download
http://sg.asus.com/Notebooks/Superior_Mobility/S46CM/#downloadBIOS 311
To disable CSM when SecureBoot is enabled.
BIOS 307
1.To disable CSM when SecureBoot is enabled
2. To hide "Secure Boot Mode" option when a system is configured for Preloaded-Win8 case
3. Fix the issue that SecureBoot will be disabled if BIOS is updated by EzFlash or WinFlash
BIOS 305
1.Update Intel ME Firmware
2.Fix lojack function fail under Win8
Looks like
there is no way to turn off secureboot and turn on csm (like the suggested solution)
There is only fast boot and Launch CSM options in the aptio.
When I turn on CSM, fast boot option is hidden.
I turned on csm (saved changes) and bring up the boot option choice, I still don't see cd/dvd drive option
Furthermore the next time i boot into aptio/bios I see CSM disabled like something went wrong. I did turn it on and I did save changes but everytime I go back to check it is off again.
I'm wondering is it possible to roll back my bios to 305 given im already using 311. Or is there any other way to allow me to boot from cd/dvd.
Thanks in advance!