2. Definite Posibility. GTX 770 typically requires 42A on 12vRail and 600w psu as a generic rule. The BeQuiet PurePower L8 530w psu is an excellent psu and has 48A on 2x12v rails, 530w continuous power, 580w peak. Normally a 530w psu would be not enough, but the BeQuiet is such a good psu, that it rates as borderline maybe now, in my opinion, since under normal circumstances a very good 550w is enough to run a GTX 770.
It either will work, or it won't, close call.