Basically the SD card contains encrypted key which is required to be mounted while logged into the PC. If I pull the card away the PC will automatically shutdow

Basically the SD card contains encrypted key which is required to be mounted while logged into the PC. If I pull the card away the PC will automatically shutdown. if the SD card is not mounted when the user logs in the system is automatically shutdown too. Basically the SD card only fights against using the computer. You of course could remove the hard drive and mount it in another computer, but that is why the whole drive is encrypted.