The mobo had pci-ex x16 1.0, I wouldn't gamble for it..
And for psu, If the PSU had pci-ex power cables/pin for graphic card Then it usually can power 7770 (it not to demanding card)
edit: are u sure u had 2.0 pci-ex? from msi website it was 1.0....
Aha, make sure first then if it is 2.0 indeed.