Testing on BF3 / BF4 is a waste of time
here's what i do when setting up OCs for peeps.....
1. Save a Profile at stock settings in Afterburner (profile 1)
2. Crank it up and use Heaven, valley, Firestrike to test stability
3. Test w/ Metro LL and if stable save profile 2
4. Send them home w/ instructions to leave it on profile 2 for all games, ans witch to profile 2 for BF
5. Otherwise they can look at what's under profile 2 and see how close they can get w/ BF and maybe save a new profile as 3
BF is just too much danged work
As for the OC ... heres something to aim for
http://www.guru3d.com/articles_pages/msi_radeon_hd_7770_power_edition_review,22.html
Original (GHz models) This sample Overclocked + VTweak 1250Mv
Core Clock: 1000 MHz Core Clock: 1100 MHz Core Clock: 1200 MHz
Shader Clock: 1000 MHz Shader Clock: 1100 MHz Shader Clock: 1200 MHz
Memory Clock: 4500 MHz Memory Clock: 4500 MHz Memory Clock: 5400 MHz