Lite-on LTR-48125S Nero 800MB?

I have a LTR-48125S and Nero FW is 1S05. As soon i insert an empty 800MB CD-R and run Medium Info it says 703MB free disc space. What is wrong? Do i need a newer Firmware? Or a newer Version of Nero? Can anyone help?

Updating your firmware is your best bet.

Nothing is wrong, except that 800MB discs are not compliant CD-Rs.

There is no disc that shows more capacity than 75:59 minutes.
You have to overburn them and hope that it works in your drives.