Nero does not recognize the 800M(90 minutes) CD disc automatically. It's still detected as 700M(80minutes) now.
If you need to burn a full disk of nearly 800M data, you can enable 'OverBurn' feature.
In Nero Burning ROM/Nero Express, open Options dialog.
Go to tab 'Expert Features'.
Enable CD overburning and set the time to 90 minutes.