One last idea..
With one monitor connected to the onboard video, go into BIOS setup now take a look at page 48 of the mobo manual. These should be automatic but it doesn't hurt to be specific.
Change init display to PEG
Disable internal graphics
Save the settings and shutdown.
Connect one display to 7770 leave the other disconnected. If this works then the other can be connected to the 7770 too.
If it's still not working at this point then I'd give Cyberpower a call.
Sorry.. that's all I got.
#1: Phenom II C2 955BE @ 3.6, Antec Kuhler 920, Gigabyte GA-MA790FX-DS5, Asus 5870/V2, ASUS Xonar D2X, 4 x 1gig OCZ2N1066SR2GK @800, Antec Truepower New 750, Arc Midi, Vistax64
#2: Athlon 64 X2 4200+, AGP 1950pro, Audigy 2, Asus A8V-D, 2gig ram, Enermax 465P, Antec900case. Now on Win8.1pro cat 10.2