Is my power supply enough for future SLI?

Hi, this is my build http://uk.pcpartpicker.com/b/G5c

I am looking to upgrade to a second 760 and I was wondering whether the 650w would cut it?

I have been looking at the Corsair RM series PSU's and I would consider grabbing one of those if required. (Those are sexy aren't they ;)

I don't really know how to accurately calculate wattage from my PC, I have used some calculators but they are suggesting 1000w PSU's which I am sure isn't correct.

I would like a PSU with enough wattage for SLI 760's and any possible future upgrades (more ram, ssd's, high performance fans and possibly a water cooler)

Thanks in advance for your help guys !

P.S I am new to the forum so apologies if I have posted in the wrong section. :)

You should be fine with that psu mate, the 760's draw bugger all power. Only downside is though you are limited to the 2x  6+2pcie cables so you are going to have to use molex adapters that came with your gpu's or grab some splitters like these >> http://www.pccasegear.com/index.php?main_page=product_info&cPath=19_1345&products_id=24644&zenid=b3fbc41d4b6cc3749c438e316f233c0a

As for adding in other things like hdds etc, dont worry you would have to have a massive array of extra gear to draw the amount of power that would be enough to warrant concern. SSD's use next to no power at all, and the same goes for hdds, most fans are only a few watts and the same goes for pumps etc.

2x 760's would make for a beast of a gaming rig btw. I hope it all goes well for ya.

650 watts is enough, but remember that a psu is most efficient at around 50% load

In that case i would recommend a 750watt psu for the most silent a efficient power supply

Watch this video http://www.youtube.com/watch?v=LiWThqgFfI4&feature=c4-overview&list=UUkWQ0gDrqOCarmUKmppD7GQ