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: FX-6350, Antec Kuhler 920, MSI 970 Gaming, Powercolor R9 290X, ASUS Xonar D2X, GSkill (F3-14900cl9d-8gbxl), Antec Truepower New 750, Arc Midi, Win8.1pro x64
#2: MSI A88X-G45, AMD A10-7850K, Asus 5870v2, Antec900 case, AMD 2x4GB 2133 (R938G2130UK), Antec 750 True, 128GB Sandisk SSD, WD Black 1TB, Win8.1pro x64
#3: Athlon 64 X2 4200+, AGP 1950pro, Audigy 2, Asus A8V-D, 2gig ram, Enermax 465P. Now on Win8.1pro cat 10.2