[Help] Mod Asus S46CA BIOS to enable Secure Boot

1.The partition is GPT.
2.Windows 8.1 is installed with UEFI actived.
3.But Secure Boot is NOT ENABLE.

I enter the BIOS, but it has no Secure Boot option. Please help me mod BIOS to show "enable Secure Boot".
BIOS version is 315.
Thanks you very much!!

It can’t be done without help from BIOS vendor and BIOS code base upgrade to UEFI 2.3.1.
If new BIOS updates won’t bring you SecureBoot - forget about it.

You are puzzled for good reason. Looking at the manual of your laptop I haven’t seen any mention of Secure Boot. Looking in downloads -> BIOS I see this for 309 changelog: “To disable CSM when SecureBoot is enabled.” Also looking here I see again Secure Boot being mentioned.
Here’s how to test:
Enter BIOS setup; Go to Boot Tab and disable PXE ROM, enable UEFI Boot. If you don’t see any Secure Boot or Fast Boot mentioned in either Boot Tab or Security Tab, set an administrative password (be sure to remember it), restart, enter BIOS setup. If you don’t see any mention of Secure Boot in Security or Boot Tab, than your BIOS needs unlocking. If you open it with AMIBCP 4.53 you will see all this options in the menu. This is just a preview, don’t alter anything without fully knowledge of the process.
Image 1:


Image 2:


Be sure that you really need or want that option enabled, as I have seen some problems with it, although MS released some updates to solve the bugs. Also take caution at what you enable and disable in the BIOS. It is your risk, after all.