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PSU calculator says 840 watts, but 700 watt works fine?

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Last response: in Components
October 8, 2007 5:50:34 PM

If you look at my computer setup it will say everything i have hooked up power wise etc. I went to the extreme overclockers page and used their PSU calculator to find out how many watts i really need. It said i need atleast about 840 Watts. I am running a thermaltake 700 Watt Toughpower psu and the 3v,5v, and 12v does not move if at all, so its stable power and what are some issues i would see if not enough power is needed because right now im just a little iffy if i need to buy a 1000 watt psu for my needs because i have alot hooked up and OC'ed too. But overall i have ran stress tests and run high end games like commander etc and never had a reboot or problem...Is it possible I am close to the limit but not over it when im at 90-100 percent load? I need some opinions/answers please. I believe i have 4 12v rails. 2 are 18amps and 2 are 20amps? :bounce: 

More about : psu calculator 840 watts 700 watt works fine

a b ) Power supply
October 9, 2007 12:57:29 AM

Those calculators over estimate power consume. That why i never use them. I base power consumption on actual power consumption measurements of the CPU and GPU from sites like, and reasonable power estimates based on prior research of other components.
October 9, 2007 1:11:24 AM

Isn't there a device you can plug in between your PSU and the electrical outlet that measures current? Kill-a-watt or something along those lines? Are they accurate?
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a b ) Power supply
October 9, 2007 1:18:23 AM

I meant measuring the power consumption of a specific component while idling or under load. modified a few motherboards that allows them to take actual power measurements of the CPU and video cards.

The kill-a-watt will only measure how much power the entire system consumes including the power wasted as heat by the PSU.'s methodology measures actual power consumption of the components after the PSU has already wasted some of the electricity as heat.
October 9, 2007 2:01:28 AM

840 watts is required?

Somebody want to check the math.

Unless I missed something, I came up with a lot less.
October 10, 2007 7:55:06 PM

My specs are in my configuration, go there to see all what I have. From reading that article is seems like my 700 watt psu thermaltake tough power is enough :p  Thanks