I cant quantify the difference in battery usage, but battery usage will
increase slightly.
However, since the graphics card has its own memory/processor it relies
less on the system resources. Allowing for CAD program to utilise the
system resources. This would certainly aid battery life.
Fan noise, temprature may be inevitable.
If you want to get more out of your battery then have a look at the
following link.
http://groups.google.co.uk/group/Lap...6458814d?hl=en
Hope this helps.
Regards
Battery Wizard
http://www.ComputerBatteries.co.uk