550 vs. 650

[justinj6]

I am wondering between these two Corsair PSUs which is the better choice and why given the price is the same after rebate.
550 Watt http://www.newegg.com/Product/Produc...82E16817139004
650 Watt http://www.newegg.com/Product/Produc...82E16817139005

I would assume it's the 650 but don't really know. Any thoughts.

Thanks,
Justin

 

[HOOfan 1]

The 650W is rated for 100W more....I wouldn't really say either is better performance wise...but the 650W obviously is good for 100W more. They are made by different OEMs though.

 

[Henry Chinaski]

Both are high quality PSUs which perform very well. But at the same price, in my opinion, there is no doubt. Go for the TX650.

 

[Emulex]

do both work with cheap back-ups (non-sine wave)? pure-sine battery backups are significant expenses. usually active PFC 85-94% like to see a pure-sine. tolerance is something that can vary within a single product batch.

Keep in mind the reason to right-size is simple. the 80-94% efficient power supplies are not efficient at 40% load. So when you do redundant power these days you want to run one at like 6% and the other at 94% to maximize the efficiency rather than a 50/50 load which results in two power supplies being inefficient.

efficiency maps are a good place to start to look.

 

[HOOfan 1]

Most power supplies are MOST efficient at 50% load...they are less efficient at low loads and high loads....who said anything about redundant PSUs?

 

[justinj6]

Thanks guys, so the conclusion in this case, go for more horsepower. Calculated my usage at about 320 watts with this upcoming system, so the 650 seems the right choice.

 

[Meghan54]

Keep in mind the reason to right-size is simple. the 80-94% efficient power supplies are not efficient at 40% load.

Sorry, but where do you get your misinformation?

A power supply Bronze rated in efficiency is rated at 20%, 50%, and 100% of rated output and must be 82%, 85%, and 82% efficient at those loads.

"Regular" 80Plus cert. is 80% across all the above mentioned loads.

Silver is 85%, 88%, 85% efficiency across those loads.

Gold is 87%, 90%, 87% efficiency across those same 20%, 50%, and 100% of rated output loads.

So, given the above figures, how can a power supply that's rated for any 80Plus certification level be inefficient at 40% of rated capacity.

Now, if you'd said 10% of rated output, then you'd have a point due to most power supplies being quite inefficient below 20% of rated output, but some new units on the market do indeed manage to maintain >80% efficiency even at 10% loads.