In order to use "Internal" secure erase on Asus P67 motherboards, you will have to do the following.
1, Enter the UEFI by pressing DEL when starting the PC.
2, Goto the advanced settings.
3, Select the SATA options, and enable "Hot plugging" on the port where you have your SSD connected. This is required as the UEFI locks the drive.
4, Download the live distro of
Parted Magic and install it to a USB pendrive.
5, Unplug the SATA power from your SSD.
6, Boot to Parted Magic.
7, Connect the SATA power to the SSD and wait a few seconds.
8, Select "erase disk" from programs menu
9, Select internal secure erase
10, Select the SSD from the menu
11, You will get a popup saying the password is "NULL" This is fine, select OK.
12, You'll get a popup asking if you wish to use "advanced secure erase" Select NO.
Your done, give it a while to erase the drive.