reload3

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Jan 23, 2012
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So I currently got a 600W PSU, but I'm upgrading my computer for abit, this is how it will look like:

CPU : Intel Core i5 2500K @ 3,3 GHz
MoBo : Asus P8H67 (B3)
RAM : Kingston RAM 4 x 4 GB DDR3-1333
GPU : GeForce GTX 570
SLI : no

So please can you tell me if 650 will be enough for this and if so if I think about 2x GTX 570 for near future if I need more then 650W?

EDIT: Thought it was 550w but apparently is 600W
 

Scotty99

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Aug 21, 2010
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Yes, overkill even. 570 requires a PSU with 38 amps on the 12v rail and 550w. For SLI you are gonna wanna shoot for a 850w PSU with a 70amp+ 12v rail. Just remember amps are far more important than wattage ratings, for various reasons!
 

ram1009

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Shooting for the smallest PSU to get you by will definitely get you in trouble eventually. Personally, I try never to run a PSU at more than 50% of rated wattage. My advice is to buy the largest QUALITY PSU you can afford. Obviously, this will cost you a little more up front but IMHO it is the cheapest insurance you will ever buy for your rig as PSU issues will often show up as random unpredictable and unidentifiable events. Stressing a PSU is never a good idea.

 

Scotty99

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Aug 21, 2010
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That is really poor advice ram.

You want to run a PSU in its sweet spot, which is usually 80-90% of its rated wattage, this is where they run the most efficient.

You also need to realize amps is far more important than any wattage rating a vid card manufacturer gives you. For example, a 570 on its own will never consume more than around 330 watts, even overclocked. An i5 will never go over 110watts of power overclocked, leaving a generous 100w as a reserve for HDD's and what not.

The biggest mistake people make when buying PSU's is actually getting one with too much power for their systems, you want to match things together so they run the most efficient. A 550w PSU with a 40 amp 12v rail is perfect for any single GPU setup with an overclocked i5, like this:

http://www.newegg.com/Product/Product.aspx?Item=N82E16817151094
 

I agreed with almost evrything you said...well, everything except the above. The efficiency sweet spot for most modern, good quality PSUs is 40-70% of max load...a nice looking little bell curve. Great PSUs like the Seasonic S12II series have great efficiency numbers (over 80%) from 20% to 90% load.

Edit: While I agree that a good quality 550W PSU will power almost any single-card PC. The OP also specifically mentioned that he wants to SLI his GTX570 in the near future and that will require a beefier PSU; 750W with 58A on the 12V rails and (4) 6-pin 75W PCIe connectors.