PSU. how do i know how much wattage i need?

[Andyclan]

Like the title says, how do you know how much wattage u need for ur computer?

Im in the process of building my first one. its a middle of the pack gaming computer. im going to spend about $550 to $600. nothing fancy. a buddy of mine told me to go 850W+. and i thought that would be overkill and i would only need about 700 MAX. he said the more the better, and it doesnt hurt to have a lot of wattage. but ive read that too much, or too little can be bad, and u need to find that middle ground.

So IS more better? is it better to be safe than sorry? or is there a guideline type thing u follow to calculate?

[Quincey]

well having some 'spare' wattage can help future proof your computer a little bit... but power requirements have not gone up that much at all in years.

Of course it depends on the system, what you are running, how many gfx cards to support etc, but usually 700 watt is plenty.

[Daverid]

Depends mainly on the Graphics Card and CPU... If your computer build is only going to cost like $600 I'd say based on how expensive the GPU/CPU for that would be, a 650/700 Watt PSU would be plenty.

Personally I have a 1200 Watt but that's because I generally do multiple Graphic Cards, Overclocking, Tons of Harddrives etc. Definitely not enough Wattage can be a problem, but I've never heard anything about having to much being a problem.

[oplawlz]

Just depends on how much you plan on drawing. From your description I'm guessing single video card and a small atx or micro atx case, meaning not much draw for cooling . . . a good 650w power supply should be more than enough. That being said, if you decide to run a bunch of usb powered devices and some kind of crazy hard drive array, things might get wonky.

[Deleted]

http://extreme.outervision.com/psucalculatorlite.jsp

I recommend this. I was recently upgrading an old desktop from 3GB RAM, 8500 GTS and Core 2 Duo E4500 to 6 GB RAM, an HD 6670 and a Core 2 Quad Q6600 and found that I didn't need to invest in a new PSU at all and the old 300 W stock model works fine. This is well within the predicted power consumption for my PC. The machine is running fine and I have had no issues yet with gaming or processor intensive tasks such as quantum chemistry code.

[BicycleMafioso]

Nothing (current) you can build today with just one GPU will require more than 400w.
520w is recommended because of people being paranoid.

More is definitely not better. More W won't increase your FPS by even 1%.
On the other hand, there is no need to be "just enough either".
But then again, going 850w because you "might add another GPU later" is not going to happen in >95% of the time, so you'd be better off with a 650w so you could cover that expansion anyway and not kill efficiency.

[Deleted]

pop the details in here
http://www.corsair.com/learn_n_explore/
in the Power supply finder. You will be surprised.

[Deleted]

To add, you will only need a PSU above 300 W if you plan to be using a higher end CPU and GPU combination with multiple drives. Even then, a 500 W unit with good efficiency should be more than enough.

[Deleted]

Nothing (current) you can build today with just one GPU will require more than 350w.

Im thinking a system with a 7970/7950/680 will probably pull a bit more than that.

[BicycleMafioso]

pop the details in here
http://www.corsair.com/learn_n_explore/
in the Power supply finder. You will be surprised.

HAHA, wow. Yes, I was really surprised. They recommend me a 1250w PSU. That can't be to sell it, right? I'm running a 650w PSU at <80% load.

Bad calculator in my opinion.

---------- Post added 2012-09-08 at 12:08 AM ----------

Im thinking a system with a 7970/7950/680 will probably pull a bit more than that.

Even a HD7970 in a rig with an overclocked i7-3960X pulls less than 350w from the PSU (but more from the wall itself).

But fair point, I shall do an edit.

[Deleted]

http://extreme.outervision.com/psucalculatorlite.jsp

I recommend this.

This is now on my Hardware Guide Favorite list. Thank you

HAHA, wow. Yes, I was really surprised. They recommend me a 1250w PSU. That can't be to sell it, right? I'm running a 650w PSU at <80% load.
Bad calculator in my opinion.

Seemed pretty accurate (using my system) comparing it to the other PSU configurator that was posted http://extreme.outervision.com/PSUEngine
Both Suggesting a 500 Watt. Either way the Corsair one has been replaces the the other one as it has way more customization.

[BicycleMafioso]

Seemed pretty accurate (using my system) comparing it to the other PSU configurator that was posted http://extreme.outervision.com/PSUEngine
Both Suggesting a 500 Watt. Either way the Corsair one has been replaces the the other one as it has way more customization.

You mean you are using the Corsair one? It had no customisability at all to me.
I use a modified version of the Outervision one posted, http://www.coolermaster.outervision.com/advance.jsp for more rudimentary things.
It's less inaccurate than the others.

[Blackmist]

If you get a decent brand, you'll typically need less wattage than if you get a shit brand.

600 will probably be plenty for almost anything under £1000. Power requirements are going down, not up. The silly season that AMD started is all but over. Intel stuff is very efficient.

[Deleted]

You mean you are using the Corsair one? It had no customisability at all to me.
I use a modified version of the Outervision one posted, http://www.coolermaster.outervision.com/advance.jsp for more rudimentary things.
It's less inaccurate than the others.

No the Corsair one (which I First suggested) and has very few options (CPU, HDD, GFX)
showed a very similar PSU to second site http://extreme.outervision.com/psucalculatorlite.jsp Which has a lot more options.