Accuracy of Power Supply Calculators?

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S3th13

Gawd
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Aug 2, 2007
Messages
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After using this power supply calculator:

http://extreme.outervision.com/PSUEngine

I was recommended atleast a 694 W power supply after upgrading to a 4870X2. My question is, will upgrading to a PCP&C 750W or Corsair 750TX be too low of a wattage? I've always thought you should upgrade to a power supply that was at least 100 watts higher than what you were drawing even though both of those power supplies have great +12V rails and excellent reviews.

Second question, are those calculators even accurate?
 
Tough question. Ok, IF you have a technical background and IF you really understand WATTS vs. AMPS vs. the VOTAGE relationship, they are useful to a degree.

I have yet to see one of those under calculate, no fear of that. Usually they error on the side of bigger is better and as a rule that is better than a bad guess or recommendation of a PSU that is too small.

Paul Johnson has kindly put his opinion in the stickys and it is worth reading.

I am in the PSU that is rated 30+% or a bit more OVER what you really need. Longer life, cooler running all at no discernable cost to your power bill.

Hope that helps you to next question;" Which power supply do I need";)

Ninja Edit: The Corsair will do you just fine:)
 
I prefer looking through HardOCP and other hardware review site rules to spot a system similar to what I'm building, and look what they measure under full load.

Aim to keep max load at around 60% of power supply capability so it will last a long time, I have some room to upgrade, and it stays within it's high efficiency region.

For example, H's review of the 4870X2:
http://www.hardocp.com/article.html?art=MTU0OSw4LCwxNjA=
540W at the wall means power supply was having to supply the system 540 * .80 = 432W being supplied by power supply.

But that was with a quad-core, extreme edition Core2 and power hungry nforce 790 chipset. Looking at your system, only a dual core core2, and a more modest P35 chipset, I'd say that 432W estimate is on the high side but a good place to stay. And *if* I was building new I'd aim for a 600-700W quality power supply. Gives overhead for more drives, or video upgrades in the future. Also for your water pump.

If you had a good quality 500W, for example I have a Liberty 500W, if I was making your upgrade, I'd keep this PSU and not worry about it.
 
Thanks for the quick replies! Extremely informative and helpful in making my power supply decision. Unfortunately, I don't have a good quality 580W power supply similar to your liberty.

If you guys had to pick between the PCP&C 750 and the Corsair 750, which would you pick? Based purely on quality, longevity, and brand recognition. They are so close in cost, I don't really mind buying either.

Thanks once again!
 
S3th13 said:
Thanks for the quick replies! Extremely informative and helpful in making my power supply decision. Unfortunately, I don't have a good quality 580W power supply similar to your liberty.

If you guys had to pick between the PCP&C 750 and the Corsair 750, which would you pick? Based purely on quality, longevity, and brand recognition. They are so close in cost, I don't really mind buying either.

Thanks once again!
Click to expand...
Both are going to be excellent. Many PCPC power supplies have 80mm's which aren't the quiestest. If that is so for that model, I'd get the Corsair.
 
S3th13 said:
Thanks for the quick replies! Extremely informative and helpful in making my power supply decision. Unfortunately, I don't have a good quality 580W power supply similar to your liberty.

If you guys had to pick between the PCP&C 750 and the Corsair 750, which would you pick? Based purely on quality, longevity, and brand recognition. They are so close in cost, I don't really mind buying either.

Thanks once again!
Click to expand...

As I said, after great care, I would go with the Corsair. Top notch service, the rep is a forum member and the test reports here on the [H] confirm my choice;)

Luck man, enjoy:)
 
Sounds great then. I'll be ordering the Corsair tomorrow. Thanks for the help.
 
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