Looking for power supply recommendation.

[bacon8tr]

I have two XFX 6770's that I would like to crossfire.  My question is, what is the minimum power recommendation.  I asked for minimum but will take it higher, as I do not like operating in the minimum power ranges.  Thanks in advance 

[titanic3]

A good 750W will be fine, if you overclock, 850W.

[bacon8tr]

Nope...learned my lesson on over clocking .  Thanks for the reco sir.

[Masherbrum]

A "No BS power supply" and will leave some overhead.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817151087

[Denniss]

A radeon HD 6770 is specified with 108W TDP and they only rarely exceed this. So what's the rest of your system you need to power with the spare 550W of the linked PSU ?
Depending on your hardware a good 500-600W PSU is more than sufficient as long it's not an el cheapo PSU from Ebay.

[Bino]

A "No BS power supply" and will leave some overhead.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817151087

 +1

I've had one of these running flawlessly in my rig for 2+ years:  http://kenshelby.us/docs/pc-parts

[deadstikmac]

In my humble exp... Thermaltake or Corsair 900W PSU.

Why those brands? They are topend psu with next generation cooling properties built into the psu along with super quiet fans. Some of the come with lights built in also. Cool & Quiet.

Why 900W PSU?  With two video cards and not much more a 750-800 might cover all your needs... However when you add Rudder Peds, Flight Stick, Headset, TrackIR, and any other usb device, you want to error on the side of more than needed to elimnate any would gremlins that cause power surges or system instabilty with power consumption.

I hope this helps....


 ~<DeadStickMac

[1701E]

A "No BS power supply" and will leave some overhead.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817151087

Same PSU I just bought about a month ago, works great.
Not to mention is comes with a shiny box and bag for wires!


As a note, bacon, a single 6770 uses about 1/2 the power (~7watts more) of a GTX 260, so two I'd assume use no more power than a 260 really (source). I run a 260 off the mentioned PSU with 0 issues. Powers the 260, AMD Phenom II, 4GB RAM, HDD, 5 fans/controller, LEDs, DVD, etc.

[Noir]

as everyone said, get a seasonic.

[BaldEagl]

A radeon HD 6770 is specified with 108W TDP and they only rarely exceed this. So what's the rest of your system you need to power with the spare 550W of the linked PSU ?
Depending on your hardware a good 500-600W PSU is more than sufficient as long it's not an el cheapo PSU from Ebay.

Since I always see you here recommending the minimum PSU needed to boot Windows I'm curious if you accept liability for your recommendations?  Will you buy him a new PSU (or maybe even a mobo or CPU or GPU) when the 500W you recommended fries?

My system is nothing special and in only a few years I burned up a PC Power and Cooling 750W Silencer which was a solidly built, highly recommended PSU at that time.  Now I run an 850W Corsair.

I'd always recommend erring of the side of too much, not "just enough".

[Noir]

power supply calculator

http://apc.canardpc.com/

[Bino]

power supply calculator

http://apc.canardpc.com/

According to the site Noir cited, my rig's draw at maximum vs the PSU maximum on the three rails and total:

+12V Rail : 43.66A  /  62A
+5V Rail : 12.42A  /  25A
+3.3V Rail : 10.17A  /  25A

Total Power : 619.9 Watts  /  750 Watts

[Skuzzy]

In my humble exp... Thermaltake or Corsair 900W PSU.

Why those brands? They are topend psu with next generation cooling properties built into the psu along with super quiet fans. Some of the come with lights built in also. Cool & Quiet.

Why 900W PSU?  With two video cards and not much more a 750-800 might cover all your needs... However when you add Rudder Peds, Flight Stick, Headset, TrackIR, and any other usb device, you want to error on the side of more than needed to elimnate any would gremlins that cause power surges or system instabilty with power consumption.

I hope this helps....


 ~<DeadStickMac

Top end Thermaltake and Corsair power supplies are made by Seasonic.  If you open up the supplies you will find the same exact components.  The only difference is the color of the case and the label on the supply.

A "No BS power supply" and will leave some overhead.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817151087

That is a good choice.


Too big of a power supply can work against you, depending on the supply design.  Switcher power supplies work best when they are under about 80% load.  Less than that and you start getting more ripple in the supplied voltage which can actually cause components to run hotter than they would normally run.  Hard drives make a little more noise, fans are not as quiet and so on.

Do not forget that at power up time there is a surge the power supply has to deal with.  Most quality supplies can actually output higher than they are rated for X number of milliseconds which normally will cover the start up surge.  This is one area cheap supplies forego.

[Chalenge]

Yes the only way to be sure is to measure the load. The calculators are a fallback.

As to ripple: you can think of the the electronic path as a pipe and the supplied current with ripple as a fret saw if that helps. Not a good thing.

[bacon8tr]

Gents, a big thanks for all the suggestions.  I have just bought my new PS and anxiously await its arrival.  My next project: cable management