Asg, everything's very efficient these days. They just need the same juice as old-generation products, but are much faster. I used to run my HD3850 off a 400Watt PSU, just like mentioned in the specs as a minimum. Well the PSU was a crappy chinese one, and very old, so I'm guessing it put out about 270-300 Watts... And those not steady at all. Once I got a new HDD I started getting power BSODs and got a 600Watt one... And I'm telling you this is gonna be enough to do a dual GTX760, if used with a low-wattage CPU (80-ish watts... Not 5 thousand, lol) You can always judge by the PSU's connectors. Manufacturers have standardized amp ratings (and thus wattage) for each connector. So if you see a PSU with dual 8-pin connectors, it means it can support such a GPU. And keep in mind that 2x Molex = 1x 8-Pin PCI-E Connector.
Well, I know Hitachi makes TVs, Batteries, and so on, so I'd expect WD, which is a company that makes HDDs and nothing else to be much more reliable... Plus I don't like the name, sounds cheap and chinese xD I think 600 Watts would do, yes. I mean, heck, those 1kW PSUs can run dual GTX780s in SLI, how can't half of that (500 Watts) run at least one? And the 760 is much less power hungry than the 780... So 600 should be enough and future-proof.
Well, that makes me change my mind. I have a 320 gb Hitachi from an old HP that a recently formatted to make compatible with my mac (had about 36 partions). I was thinking that maybe 600w would be appropriate.
=========== @bmc Here's a chart I found on HDD reliability: [Clickety Click] It seems like very chart suggests that Seagates are the least reliable drives, although I wouldn't agree on Hitachi being the most reliable. As for the PSU, 750W should be more than enough