jr9 :
Power supplies also lose wattage over time
Now these here are sort of muddy waters. This isn't necessarily true. Good PSUs will be perfectly fine and doing their full output continuously for many many many years without maximum power ever decreasing. Even if electrical performance were to decrease, electrical performance is not really the same thing as power. You can have worse electrical performance but the same amount of power, and many people confuse one with the other. In other words, this is a myth.
jr9 :
Uhh we are sure because they don't leave it to the marketing department to determine the ideal power supplies needed for their cards
This implies that ideality, that is, what makes a power supply ideal for a particular context, is most importantly wattage. I find the fan and soldering to be much more important than the labeled wattage. The fan is the first thing to fail on most power supplies, and soldering is very important for the longevity of a power supply.
jr9 :
If you are 100-200 watts over what you need/load that is ideal.
But where is the argument? You are stating what seems to be a conclusion with no supporting argument. I don't think it's ideal. I think the notion of "ideal" pertaining to a certain wattage doesn't go well when the power supply has so many other things that are more important than the labelled wattage.
jr9 :
The PSU will last longer and the card will not fail when it's not constantly being pushed
The graphics card pushes the power supply, not vica versa. Also, it is not necessarily true that a PSU will last longer if it's under lighter loads. We like to think that's true, and people assume it, and it's probably true most of the time, but it really depends on what it is that is going to fail first in a power supply. It really is going to be particular to a certain context. Not one thing applies to every case. And remember, buying a high quality 450W power supply is better than buying a low quality 600W power supply. I say this assuming it's true, but arguably this is a general consensus. Give me an FSP Hydro X 450W any day over something like an EVGA 600B. I get a much better fan, better performance, and it should last much longer. On the other hand, the EVGA 600B has a higher labelled wattage. But what does that even mean? If you delve into it you'll find... it depends...
jr9 :
If you are building a PC you never cut it that close on wattage.
But your close is not my close maybe. Or someone else's notion of closeness is not ours.
Anyway, I do really enjoy discussing this stuff with you. Like legitimately, I'm not being sarcastic.
Regardless, it'd be nice if OP updated us with some details of his system specs. He might have the EVGA 450B3, which is actually pretty good if you like dealing with some risks.