AutoCAD LT

[#1]

I hope someone can help me. I have recently purchased 4 Radion Saphire HD6850 graphic cards for 4 HP Z400 workstations on a recommendation from somewhere, but I have read on the web that possibly these arent any good for CAD. Can someone pleasee enlighten me as too whether they would be ok as my supplier wants a 10%restock fee to send them back. They are unopened. 

thanks

[#2]

What's the rest of the system like, and what Windows (and AutoCAD/LT) version?

And why did you buy a new Vid Card if I may ask?

[#3]

Hi,

sorry I was a bit vague.

The workstation is a HP Z400 Windows 7 64bit with 6Gb RAM, Xeon quadcore processor.

The workstation didnt come with a graphics card, so thats why I had to purchase one seperately

[#4]

still missed a bit, LT 2012 is the version.