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How to calculate how much watts a PC needs?

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  • Gtx
  • Components
Last response: in Components
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October 8, 2014 8:13:08 AM

So, Relatively quick question here, I am wanting to become more "independent" when it comes to PSU's, How exactly do you calculate how much PSU you need to be able to run a certain GPU? Lets say, The Gtx 760, How would you go along doing that? (FORMULA'S if possible?)

Just wanting to know if I could possibly be able to do that without constantly asking if my psu could run a GTX 760, (which, I have EVGA 600B, So, Would it run? :D )

EDIT: Wouldn't it basically be a certain number of what the Actual system uses? (something around, oh, 300-400 watts? Then just applying what the GPU uses? Or is it more complicated then that?

More about : calculate watts

October 8, 2014 8:15:26 AM

It should be fine. A GTX 760 with a non-overclocked Intel system will run comfortably on a 450w unit.
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October 8, 2014 8:16:41 AM

I'd go to Game Debate or TechPowerUp's database and look up for that card's TDP. 170W, add 100W for CPU, another 50-80W for MoBo, RAM, HDDs, etc, and 100-200W for headroom. 500W minimum and 550W or higher recommended, so yes, yours is just fine, a good quality PSU :) 
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October 8, 2014 8:19:17 AM

Forget the rocket science.

99% of computers you only need to know what the graphics card is.

Google "GTX 760 powerr supply requirements"
You'er done.

Now if you have 6 or 8 hard drives in a RAID, or some other unusual set up, you might have to add a little.
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October 8, 2014 8:26:28 AM

What I usually do is something like this: (graphics card's TDP + CPU's TDP + 150w for other components) * 1.2
That way you'll have a more than sufficient PSU wattage and never getting close to 100% load on the PSU. It's nice and safe.

This calculator also works and also overshoots.: http://www.extreme.outervision.com/psucalculatorlite.js...

In reality a PSU with a wattage of
(0.9 * CPU's TDP) + graphics card's TDP + 75-100w
will generally be enough but I'd recommend getting a PSU with a little higher wattage.


Also, amps on the 12v rail(s) are generally more important than wattage.
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October 8, 2014 8:29:26 AM

Well, Those were the fastest reply's I've had ever, I do use the Xtreme Calculator, Really do like it, Just was wondering what else i could do, I do plan on overclocking and stuff, so, yeah, Not the cpu in anyway though, just the GPU, my 600B has been holding up quite well with the +200mhz on my GTX 750ti, So, Wont be upgrading anytime soon yet, But, I'm debating between either the 760, 970, or hopefully upcoming 960, But, I suspect the 760 should be lower in price when they come out.

Anywho! Thanks for the help guys!

EDIT: ah yes, Amps on the 12v, Again, thats another question i forgot to ask, How do you calculate that? :D  Sorry to bug you guys.
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October 8, 2014 8:32:04 AM

No worries, you may visit, ask, or just hang out on the forums to be updated with the best value/money cards. Right now R9 280 is tad better than 760 while being cheaper, and guess what, your PSU can run it! Even a 280X for that matters, its a good enough PSU. Glad to help :) 
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October 8, 2014 8:33:52 AM

MeteorsRaining said:
No worries, you may visit, ask, or just hang out on the forums to be updated with the best value/money cards. Right now R9 280 is tad better than 760 while being cheaper, and guess what, your PSU can run it! Even a 280X for that matters, its a good enough PSU. Glad to help :) 


Yeah, I'm still more of a Geforce guy, Always have been, I've tried the radeon r7 240 (had to upgrade from the GT 620) And, it was a okay, Still went back to Geforce, :D 

Incase you haven't seen, How do you calc amps for the 12v on GPU?
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October 8, 2014 8:35:54 AM

Well, Power=Volt*Amps. So, 150W GPU needs 12.5A from 12V line. Damn I used the calc for dividing 150 by 12.
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Best solution

October 8, 2014 8:36:15 AM

Amps = wattage / volts

So for a GPU it's: amps = TDP / 12
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October 8, 2014 8:38:39 AM

You don't.

A few cards will list the required amps, but it is rare.
The 4350 had an amp rating because it was so high at the time.

Just buy quality and the right size.

Volts X Amps = Watts, in case you didn't know.

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October 8, 2014 9:46:07 AM

Thank to you all guys! :D 
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October 8, 2014 9:48:12 AM

Glad to help :) 
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