jpolk1138, I'd say with a substantial budget like $2000 you probably should get a power supply with as high efficiency as possible. Although it doesn't absolutely have to have any kind of 80 Plus certification at all, as long as it is high quality. As I explain below it is unlikely that you will find a high quality PSU these days without an 80 Plus certification, so I would say aim for Silver/Gold/Platinum.
If you are looking at 750W+ PSUs then your intended system should have at least two power hungry graphics cards.
If you want your PSU to be quiet then you should also make sure that the rest of your system is quiet, otherwise you probably wouldn't hear your PSU even if it was loud.
There is a theory that more efficient PSUs are quieter than less efficient PSUs because they have to dissipate less waste heat. However it is not as black and white as that; companies can still choose to use loud fans in their 'more efficient' PSUs.
cl-scott :
By and large, the whole 80+ program is purely marketing gimmickry and has no real-world application.
Agree that the 80 Plus 'program' is marketing and not much more.
cl-scott :
I would have to double check the specifics, but the general system of the 80+ program is that the PSU is at least 80% efficient at very specific load levels. I believe they are 20%, 50%, and 100%. There is NOTHING in the 80+ specification that says the PSU must be similarly efficient at any other load level which is where your computer is probably going to be 90%+ of the time. Now I will say that there is a fairly sound line of reasoning that says if a PSU is some minimal efficiency level at certain loads, it's probably going to have something of a bleed effect to other load levels. However, how much would vary PSU to PSU, and it could be anywhere from equaling efficiency at measured load levels for the 80+ program all the way down to no added efficiency.
As far as I'm concerned the only reason to doubt the efficiency claims made in an 80 Plus report is if the manufacturer/brand selling the PSU sent a cherry-picked or otherwise unrealistic unit to be tested by Ecova, in other words if the brand/manufacturer is not trustworthy or trying to get a competitive advantage it hasn't truly/honestly earnt.
Plenty of reviews show that good units, which have been 80 Plus certified, have an efficiency curve which is pretty straight; they don't very often, as you seem to suggest, fluctuate/dip between 20% and 50% or 50% and 100% loads.
I would be concerned with the efficiency below the 20% mark, because as a lot of people oversize their PSUs and spend most of their time in idle they are using less than 20% of the unit's capacity '90%+ of the time'.
However the efficiency aspect is not what is important to highlight IMO, it is the fact that it is only about efficiency, it is not about quality, or performance. Which are obviously more important factors in deciding on which PSU to buy.
cl-scott :
So I would say by and large there is no particular reason to get an 80+ PSU unless maybe there's a good deal on one or you've done the math and figured out that you will be at one of the measured load levels a significant portion of the time.
Apart from the fact that it is quite hard to find a high quality PSU these days that isn't 80 Plus certified.