ugh, I leaning towards a no. personally I'd look at 750+W for dual 560s.

12V x30 x2 = 720

I think the PSU is rated to trip at 38a, but I seriously doubt it's designed to supply both rails at 38a continuously.

moreover, each 560 needs 2x6 connectors from the PSU, while you only got 2. So there you go.