PSU, enough power?

nbrikha

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Quick question. I don't think there's going to be an issue with this. But still have to make sure. I'm running a Phenom II x4 840 on a Sabertooth 990FX. I have a Cooler Master eXtreme Power 600 Watts. I have an XFX 5770 and I want to crossfire an HD6770 but I want to make sure before I buy it that my PSU is gonna be sufficient. I have about 5 fans running too. Am I in the clear?
 
Ouch, no way. Not even in the realm of required.

Firstly, and I'm only mentioning this for folks who don't pay attention to the numbers of the cards you're going to use (different on paper, but identical in chip tech, as I'm sure you know) putting two generations into CrossFire will make your faster card throttle itself down to the speeds of the slower card (both in terms of clock speed and feature set), so you're actually doing yourself a disservice by mismatching the cards like that. Since the 6770 = 5770, it's a moot point for you, but I wanted to be sure folks saw that info in case they find this thread later and create more issues with a non similar family GPU setup. :\

Secondly, for those cards, 850 watt is overkill if you get a name brand power supply. You can easily run that setup on your existing PSU, or if you're feeling skittish about it, 600-650 watts should be fine. Two 5770's in CF only use up about 384 watts, and you'll see nearly identical performance with a 5770/6770 setup.
 
Your current PSU should be fine. This review by JonnyGuru - one of the most respected names in power supplies on the net - measured Crossfire use at peak load at 341w then went on to confirm the manufacturer's recommendation for a PSU with a minimum of 600w for the average system. Still, should you wish to do any overclocking, I recommend going to at least a 750w PSU - and a better brand.

HIS Radeon 6770 ICEQX Turbo Crossfire review

For a little insurance, I suggest running the power supply calculator at this page - I am linking the free calculator that only shows total wattage but recommend you click on the Pro and pay a couple of bucks to also calculate the power on the different legs.

http://extreme.outervision.com/psucalculator.jsp
 
6770 is a 5770 that's been updated to have OpenGL 4.1...that's why they're crossfire capable with each other. They have the same clock speed, effective mem speed, etc.

Yeah, the setup I have plus crossfire is telling me 500 watts. So the one I have should be good, if I go with this setup.

I don't plan on overclocking. But now I'm starting to think if I should just start saving up and waiting for the bulldozer eight core to come out and upgrade everything. Get a new GPU, the bulldozer, and a new psu. Now my question is, should I get one higher end card or a second gpu in crossfire with this one? In other words, should I go with a 6770/5770 in CF setup or one 6970 or gtx 570?
 
750 watts is still too much in this case. 650 maybe for overclocking, 700 is pushing it. There's just no need to spend that kind of money. If you want the unit to last several upgrades, sure, by all means, but most of the time people who "buy ahead" on power supplies have them fail down the line when they've put all their money into their system and none into a good backup battery / UPS solution and/or they get fried by lightning (even with a UPS!) and have to start over at ground zero. just things to consider.
 
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