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Old 08-21-2006, 01:59 AM   #11 (permalink)
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Its easy dude, just figure out the total max current draw of all the items in your computer and add 15-25%. Thats how many watts you will require to run your system.

For example, all the items you buy should say the voltage and amperage they draw. Simply calculate that in to watts using this formula: Watts = Volts x Amps, and shabang, add all the watts of all the items. (a typical mobo and cpu take 120-200)
Furthermore, I will give an example of a typical system:

Mobo/CPU/RAM - 180w
DVD-RAM - 5Vx1.5A=7.5W and 12Vx1.5A=18W = 25.5W
HDD -5Vx.35A=1.75W and 12Vx.50A=6W = 7.75W
VID Card -5Vx2A=10W and 12Vx2.5A = 30W
Extra Fans -12Vx1.25x2 = 30W
Other -12Vx1A = 12W
Total = 285.25W
+ 25% (71.31W) = 356.56W total required.

All this hype crap about NEEDing 500 billion watts is just a load of crap, in fact most typical systems will do just fine on a nice stable 350watt PSU. Personally it is wise to use a 400W or better for expandability, and intial current draw, but if u just want to keep it simple follow the above and u shallant go wrong.
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Old 08-21-2006, 02:30 AM   #12 (permalink)
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^^ i guess that would make sense if you were running low-end components... 30watts for a video card?! plz!!

http://www.legitreviews.com/article/354/3/

the 7950gx2 consumes 154watts idle, and 284watts under load.. and thats the card ALONE. 350-284=66watts for the rest of the system.. which = bad idea.


500 watts is a good minimum with this card.. as that leaves less than 250 for the rest of the system. the true power 2.0 550watts would compfortably feed that card.
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Old 08-21-2006, 06:18 AM   #13 (permalink)
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yep and thats quite an expensive card so i hope thats within your budget
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Old 08-21-2006, 09:17 PM   #14 (permalink)
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"We looked at the total system power consumption at idle with nothing running on the desktop."

This is straight from the 'Legit' review. And it makes sense, that TOTAL SYSTEM DRAW would be like that, and that total system draw would skyrocket when under load, especilly because the cpu will suck the most power when actually doing something.

http://www.codinghorror.com/blog/archives/000662.html

This shows more accurate specifications, the gx2 suprisingly has no idle spec, but I think its a mis-print. Its probably the same as all the others somewhere around 25-35 watts, and obviously 110 watts at full load.

Wow its amazing how 284-154=130watts differnce, being that thats total system load measured probably at the wall plug.
So 35-110=75w more at load from idle.
So the system that "Legit Reviews" had, took 154-35=114w at idle without the vid-card, and 284-110=174w under load without the vid card. Thats a 60w system difference without vid card.
60+114+110=284w total.

The #'s all make sense, when you consider that they were looking at Total System Power.

Once again I directly quote the review:
"We looked at the total system power consumption at idle with nothing running on the desktop."

Whoever wrote this obviously didnt pay attention later on in the review when they claimed that the card itself drew the watts portrayed in the review.

Anyways, I was only giving an example with the typical system setup, of coarse a high end system will suck more.

The formula works just the same, add all the load together, and then add 25%, thats how much u need.
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Old 08-22-2006, 12:52 AM   #15 (permalink)
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lol.. i stand corrected. i still wouldn't get anything lower than 500watts though, lol. in the review they used a 750watt PSU, which is overkill, but i guess they're taking their precautions... since they're using power-hungry cards.

i think when you first turn on your comp or something there's a spike in the power draw.. so i donno... you're right, it doesn't use that much power, but i wouldn't get a PSU that only has 350watts for a system with a 7950gx2 just cuz the math adds up.. you are right though.
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Old 08-22-2006, 09:39 PM   #16 (permalink)
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Lol.
Well to get back to the origional topic i guess, I think a 480 would be sufficient, however a 500 like aliasaid suggests is also a good idea to be on the safe side.
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