And the reason for that being?

I'm sure the EVGA cards can be flashed with newer bios with a higher max voltage. At least people in this thread has done it, posted a couple of pages back. Not sure if it is "FTW edition" users only...

I'm at work atm, but I could give you a better description later.
Take a look here and you'll see the top 4 bios' is the newest for GTX480's.
Revision 70.00.21.00.82 for EVGA's, for me using Zotac the revision is 70.00.21.00.02