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90% efficiency @ 50% load and 87% efficiency @ 100% load... who's nit picking over 3% efficiency?

 

Personally I wouldn't get anything more than 750. I ran the Extreme Power Supply Calculator at http://extreme.outervision.com/PSUEngine and I literally doubled everything (except processors) and it says for a 2700K build with 4 Sticks of DDR3, 2 GTX680s, 4 HDDs and 2 SSDs that the recommended PSU is <600watts. I'm looking at the AX 750 or 650. Although a modular motherboard cable is probably not worth the extra 20-30$ to get from an HX750 to an AX750.

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I think i may be the only one here that has come really close to maxing out a psu's load in recent history. I was using a 1200 watt psu to empower an i7920 and three gtx480's with a watercooling loop and under load during stock testing i was pulling 1260watts out of the wall. I really didn't do a overlooked test as i did not want to know what it was after that. Given it was a gold cm1200 edition that should place me around 1100 watts dc being used. That's why i don't do much 3way sli anymore. Too much draw period. Lol. It also makes me glad that the newer stuff is even more efficient then a few generations back.

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90% efficiency @ 50% load and 87% efficiency @ 100% load... who's nit picking over 3% efficiency?

 

Personally I wouldn't get anything more than 750. I ran the Extreme Power Supply Calculator at http://extreme.outer...n.com/PSUEngine and I literally doubled everything (except processors) and it says for a 2700K build with 4 Sticks of DDR3, 2 GTX680s, 4 HDDs and 2 SSDs that the recommended PSU is <600watts. I'm looking at the AX 750 or 650. Although a modular motherboard cable is probably not worth the extra 20-30$ to get from an HX750 to an AX750.

 

 

Frankly, these calculators are BS. to accurrately pick out a PSU, you need to calculate the AMPS on the rail(s). For instance, 2 x 6970's draw max 28 amps=56 amps. ADD the CPU and peripherals and you get your answer. Then cross reference the amps on the rail(s) of the PSU. 1 beefy rail is better than multi rails.....

 

The final total of system amps should also have a overclock if you intend to overclock. Fiinally, if the total AMPS are under 90%(preferably 80% for headroom) your good to go. Just cause a PSU says 750 AMPS does not mean it can handle EVERONES hardware.

 

IMO pushing a PSU over 80% leaves no headoom and a potential short life. You should never skimp on the PSU.

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Frankly, these calculators are BS. to accurrately pick out a PSU, you need to calculate the AMPS on the rail(s). For instance, 2 x 6970's draw max 28 amps=56 amps. ADD the CPU and peripherals and you get your answer. Then cross reference the amps on the rail(s) of the PSU. 1 beefy rail is better than multi rails.....

 

The final total of system amps should also have a overclock if you intend to overclock. Fiinally, if the total AMPS are under 90%(preferably 80% for headroom) your good to go. Just cause a PSU says 750 AMPS does not mean it can handle EVERONES hardware.

 

IMO pushing a PSU over 80% leaves no headoom and a potential short life. You should never skimp on the PSU.

 

Calculating amps on the rails isn't that hard, though. And there's typically only one component that requires amperage that an average PSU doesn't have: The GPU. Go to your GPU's product page, see what amperage it takes, and count the rails. If it requires 39A and has two inputs, you have to use two rails with a combined 39A rating.

 

It's honestly very simple to find amperage: But that doesn't mean a wattage calculator is bull. The calculator actually works pretty well: It's up to you to find the amperage because you can't "guesstimate" that as many times it's literally part dependant: Two nearly identical GPUs could require very different amperages, while requiring the same wattage: It'd take forever to design a site with amperages included because you'd have to list every model of everything ever made in those drop boxes.

 

And I agree with you on the PSU load: I try to keep mine between 50 and 70%, no more than 80% tops (as you said, leaves tight headroom for an overclock, and lowers efficiency on many PSUs after that threshold.

Edited by dragonsdontfly

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Frankly, these calculators are BS. to accurrately pick out a PSU, you need to calculate the AMPS on the rail(s). For instance, 2 x 6970's draw max 28 amps=56 amps. ADD the CPU and peripherals and you get your answer. Then cross reference the amps on the rail(s) of the PSU. 1 beefy rail is better than multi rails.....

Since most of those calculators give you a wattage rating based purely on the 12v power draw...it's not very hard to find a PSU to match up if you pay attention to the ratings of the individual rails (which you should be doing anyway).

 

It's not like it's difficult to take the wattage rating and divide by 12. :lol:

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Since most of those calculators give you a wattage rating based purely on the 12v power draw...it's not very hard to find a PSU to match up if you pay attention to the ratings of the individual rails (which you should be doing anyway).

 

It's not like it's difficult to take the wattage rating and divide by 12. :lol:

:withstupid: Beat me to it you rascal!

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