I agree that you shouldn't skimp on a PSU, but the $60-$80 range is where I like to sit, and the biggest wattage they have for that price range is 650 watts, which is a bit under what I like to sit on. (Though it'd likely run my rig just fine)
You are looking at this wrong.
Name a single part other than keyboard that you won't replace in 3-5 years.
How many PSU's have you bought and how much have spent on them over the last few upgrades? You can spend $60-$80 and keep replacing it every upgrade cycle, or you can spend a bit more ($100-$120) and not replace it for 10 years. I went through a PSU
every year before I bought this one, it's paid for itself many times over. Easily the best (possibly only!) long term computer investment I ever made.
Eh, I don't know if I would trust even a solid 650W with SLI 680s. I'd probably want at least 750W just in case.
That's fine, but it's impossible to pull 650w from the wall with two 680s and an overclocked SB/IB I7.
It's not impossible at all really.
Power supplies are broken up by voltage, exceed any of them and you surpass a PSU's capability (650 watts doesn't mean 650 watts any way you want it). The CPU and video cards, while the highest draws, aren't the only components in a system. Add enough extras and you can certainly exceed what a 650 watt psu is capable of doing over long periods and stable.
Will a common desktop exceed what a 650 watt can handle? No, however, you already destroyed that concept of a common desktop when you went with dual 680's. If you can afford dual 680's, not only are you likely not the type to remain content for long or have a very basic system, but you also certainly have the money to do it right and put a more capable power supply.
And what will your system be next time you rebuild it? You went overkill on everything, spending big bucks on video cards and a system and then hamstringing your next upgrade to save $20 on the one part that actually ties it all together and has the potential to destroy it all if it fails. It's like building a skyscraper but skimping on the foundation because no one sees it.
Second, the lower you stress a PSU, the more efficient and cooler it operates. This saves you on your electric bill and makes the psu last longer. It's also more stable, which means your components last longer and you can overclock higher.
Another thing to remember is that power supplies lose capability as time goes on. Cheap ones can lose 20% their first year and 10% the next. Better ones are obviously better, but they still lose some. Can you afford a 10% loss over 3 years? Especially as hard drives wear and consume more power?
The only good reason to go with the bare minimum is if don't plan on keeping it or you like trouble.
A lot of small problems I had went away when I stopped skimping on PSU's.
