Originally Posted by Unoriginal Sin
Because overdoing it too much will end up costing you more in your actual monthly electricity bill, that beside the initial higher cost.. if you like to spend money on power you'll never use fell free to do it.. however, that doesn't mean it's smart or wort sharing, because it's not.. it's pretty stupid and points to the fact that you're not very sure about what you're doing.
As far as multi GPU configs go, you could at least ask him if he intends to do such a setup before suggesting he should spend money you didn't earn for him on stuff he'll probably never use
Your PSU doesn't consume power, it only converts it, and loses some in the conversion. Efficiency is what you're talking about, not rated max wattage.
Ex. if system draw is 300W, a 1500W 80+ silver PSU will draw noticeably less power than a 350W not 80+ certified unit. However, power is relatively cheap, so don't spend $100 more for an 80+ platinum PSU with the idea that it will save you money; especially if system draw is relatively small.