Also remember that the Corsair CX750 only has 2 x pci-e plugs and the S5 needs 4. You could probably use molex to pci-e converters but I'd be wary putting that wattage / amps through them because they can get hot and even melt which is obviously a fire risk.

In all honesty you're better off going for a branded psu with minimum 4 pci-e connections or a server supply with the same. Please take a look at Dogies psu guide if you need any help with an atx unit: https://bitcointalk.org/index.php?topic=486121.0.

If you're thinking about getting another S5 in the future then the EVGA Supernova 1300 or 1600 look just about perfect for the job as philipma1957 mentioned a few posts back as they both have 8 pci-e connectors.