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PSU WATTAGE LIES??!

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October 27, 2010 5:08:03 PM

:sarcastic:  Hi Everyone, I hope all is well.
I have a question that has been bothering me for some time now.
PSU manufacturers recommend very large Power supplies to run High End Computers. In this youtube video http://www.youtube.com/watch?v=z8KkMkTZs58&feature=rela... .
The Guy in the vid has a beefy i7 SLI GPU , and his system never requires more than 320W. If you enter his systems specs on most of the online PSU calculators they all reccomed at least a 650W PSU. Can anyone please help me out. I'm really confused. Thanks so much!

More about : psu wattage lies

October 27, 2010 5:27:39 PM

Was the guy actually using his GPUs for 3D use, such as gaming? Most cards idle at far less power than they would use at load.

I know that if you check the power consumption on the cards, they usually draw 75w from the PCIE slot and another 75w or so from each connector from the PSU. They don't always use this output, but if at max, they can.

Check out some of the benchmarks here and at anandtech to get some real numbers. A multi-GPU setup could easily put you up in that range.

Also, please remember that you don't want your PSU running at 95 or 100 percent. There is a zone that it will perform well...someone here will help me on it, but I think it's between 50 and 80.
October 27, 2010 5:29:31 PM

In the Vid it he is gaming

Thnx

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a b ) Power supply
October 27, 2010 5:48:07 PM

I have one of those P3 Kill-a-watt, they arent always as accurate as they should be. One of the reasons PSU manufucturers recommend the higher wattage PSU's is that they will have more AMPs on the 12V rails. A 320watt PSU wont have enough AMP's on its 12v rails to power those 2 GPU's, you need a higher wattage like a 650 watt. Also if you are running you PSU @ 100% capacity it will wear down the PSU faster, and when PSU's wear out they will either become inefficent or not put out the required wattage needed by components, a large PSU helps avoid this issue.
For reference my C2D @ 3.5 with 4 hard drives and a 4870 repords under full load as around 300 watts full load GPU-CPU (with my P3 kill-a-watt)

I made a comment on that guys video because he thinks 80% efficent means that a 400watt psu will only output a max of 320 watts, and his 650 will only do 520 watts. All hes doing is making more people misunderstand what an efficency rating is.
October 27, 2010 6:21:47 PM

Snipergod87 said:
I have one of those P3 Kill-a-watt, they arent always as accurate as they should be. One of the reasons PSU manufucturers recommend the higher wattage PSU's is that they will have more AMPs on the 12V rails. A 320watt PSU wont have enough AMP's on its 12v rails to power those 2 GPU's, you need a higher wattage like a 650 watt. Also if you are running you PSU @ 100% capacity it will wear down the PSU faster, and when PSU's wear out they will either become inefficent or not put out the required wattage needed by components, a large PSU helps avoid this issue.
For reference my C2D @ 3.5 with 4 hard drives and a 4870 repords under full load as around 300 watts full load GPU-CPU (with my P3 kill-a-watt)

I made a comment on that guys video because he thinks 80% efficent means that a 400watt psu will only output a max of 320 watts, and his 650 will only do 520 watts. All hes doing is making more people misunderstand what an efficency rating is.


Great this helps a lot! thanks so much for your time.
Another quick question. So , lets say you had a solar panel. that could generate a constant 300W supply.
Lets say you have a high end machine that the component manufactures recommend a PSU of 650W, because of the " A 320watt PSU wont have enough AMP's on its 12v rails to power those 2 GPU's, you need a higher wattage like a 650 watt." Even tho your Computer only draws 250W from the killa watt meter. Would you be able to Power your PC with a 300W Solar panel-in ideal situation-even tho they recommend a 650W? What is the relationship?

Thanks again man!
a c 243 ) Power supply
October 27, 2010 6:49:33 PM

Snipergod87 said:

I made a comment on that guys video because he thinks 80% efficent means that a 400watt psu will only output a max of 320 watts, and his 650 will only do 520 watts. All hes doing is making more people misunderstand what an efficency rating is.

And he claims that you're wrong :o 
!