More than likely it is being run in Linux & they did a bios mod,which can increase the hashrate but...can void your warranty.
Linux is bit hard to learn if your old like me
I run all cards stock on Win 7 Ultimate 64bit,380 4gig=20mhs,390 8gig=30mhs,480 8gig=25mhs,580 8gig=25mhs..keep at 60-65c with fan speed & underclocking of core to around 1150 (if needed)
I think I read the 460 was around 12-15mhs stock..........