PSU calculators suck, pls help with real answer

[jme621]

so after trying like 4 online calculators and getting 4 differnt psu requiments, im just gonna ask here.

what is psu requirment for:


3 5830 http://www.newegg.com/Product/Product.aspx?Item=N82E16814102878
amd sempron http://www.newegg.com/Product/Product.aspx?Item=N82E16819103698
640gb notbook sata harddrive, its all i had laying around hehe and i know link is to 500 but it was a free upgrade thing to 640 from wd http://www.newegg.com/Product/Product.aspx?Item=N82E16822136780
asrock mobo http://www.newegg.com/Product/Product.aspx?Item=N82E16813157226
2gb ddr2 mem, one of these other is in htpc still http://www.newegg.com/Product/Product.aspx?Item=N82E16820211188
2 120mm fans 1 80mm fan non led on all

just need the range from lowest to safest bet. I have all these items already, just need a suggestion on power, thanks

[1714775763]

1714775763

[1714775763]

1714775763

[grue]

wattages are ADDITIVE. why is it so hard? go to the site of the manufacturer, look up the TDP, and add them up.

based on your specs, it would need around 700 W of power, which translates into a 800W - 1000W PSU, depending on the brand.

[phillipsjk]

It is hard, because manufacturers don't publish the expected TPD, they publish the maximum the device will draw. Actual usage depends on a lot on how the computer is actually used.

I also agree the online calculators suck. They either assume you are going to be using a crappy power supply or they are trying to sell you a bigger supply than you need.

That is without getting into the distribution of available power. Fans, Video cards, and modern CPUs (since the P4) draw most of their power on the 12V rail. Support chips will likely be using 3.3V or 5V. Modern memory uses something like 1.8V: whether that comes from the 3.3V line or 12V line is probably up to the board designer (using 12V would substantially reduce the required current, but at about 15 Watts, that would only be about 4.5 Amps at 3.3V).