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HX750 Enough for I7 OC+Crossfire?

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November 30, 2009 4:39:59 PM

When I use the psu finder on corsair.com and says I'll be using i7+58xx series crossfire+1HDD and extreme OC (30%+) it recommend me a minimum of 850 watts (hx-tx 850++). But when I use extreme.outervision.com and I says I'll be using I7 920 overclocked to 3800 (1.34V) 100%TDP+6 Stick of DDR3+ 5870 Crossfire+ 1HDD and 1SD+ 1x240mm and 4x120mm, everything at 100% peak load it says 601 watts. Which one should I trust !?!?! Is HX750 enough if enyway the maximum peak load will be 601 watts or should I trust the psu finder and go with hx850?

More about : hx750 crossfire

a c 144 ) Power supply
November 30, 2009 5:18:49 PM

Yes, a good 750 watt PSU will be more than enough. And the HX750 is a very good PSU.
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a b ) Power supply
November 30, 2009 5:57:33 PM

Personally I'd play it safe and go for the HX850 (which is more than likely what I'm doing). Just gives you a little more headroom to push your OC further and/or OC the Radeons.


Related question without wishing to hijack the thread: if a 3rd 5870 were added, would the HX850 be sufficient then? Or jump up to the HX1000?

Thought I'd put the question out there as I'm looking at triple GPU capabilities on my imminent build and thought is it worth getting the 1000W now ready for the 3rd card in about a year, or the 1000W isn't actually needed.
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a c 248 ) Power supply
November 30, 2009 8:54:26 PM

The general rule of thumb is a high quality 500 to 550 watt power supply with sufficient current (amps) on the 12 volt rail(s) can easily power a system with any single video card made. A high quality 700 to 750 watt power supply with sufficient current (amps) on the 12 volt rail(s) can power a system with two video cards operating in dual mode. There are a few exceptions like the new ATI Radeon HD 5000 series cards which use less power due to their energy efficiency.

A high quality 500 to 550 watt psu will have a +12 volt rail rated at 40 amps. A high quality 700 to 750 watt psu will have a +12 volt rail rated at 60 amps.

In addition, the power supply should be at least 80+ Bronze certified for energy efficiency.

Here are the official power requirements for the new ATI Radeon HD 5850 and HD 5870 video cards.


ATI Radeon™ HD5850 System Requirements:

PCI Express® based PC is required with one X16 lane graphics slot available on the motherboard

500 Watt or greater power supply with two 75W 6-pin PCI Express® power connectors recommended

600 Watt and four 6-pin connectors for ATI CrossFireX™ technology in dual mode


ATI Radeon™ HD5870 System Requirements:

PCI Express® based PC is required with one X16 lane graphics slot available on the motherboard

500 Watt or greater power supply with two 75W 6-pin PCI Express® power connectors recommended

600 Watt and four 6-pin connectors for ATI CrossFireX™ technology in dual mode

The power supply recommendations are for an entire pc system.


LePhuronn - I can't even remember the last time someone asked about power requirements for a tri or quad video card configuration. According to survey stats I looked at the typical gamer uses only one video card. Overclocking is usually moderate.
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November 30, 2009 9:07:43 PM

IMO I think the benefit doesn't worth the price. If you take the extremely good rampage ii gene (2gfx) vs the rampage ii extreme (3gfx), you will pay 359.99$ instead of 209.99$ on newegg. So its an extra 150$ for the motherboard. And the HX1000 instead of the HX850, you will pay 239.99$ instead of 179.99$. Another extra 60$. A total of 210$. If you were thinking about buying let's says triple sapphire HD5750( 3 x 144.99$= 435$$) with the extra 210 for the mb and the psu. A total of 645$$. If you take instead dual 4890 (2x 195$=390$). You will save 250$, you will be able to run virtually anything (don,t talk crysis plz loll) and you will have a good bang for the bucks.
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November 30, 2009 9:19:01 PM

For 2 5870, you should get at least 850 Watts.
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a b ) Power supply
November 30, 2009 10:13:17 PM

It was just a theoretical question really - in 2 years or so when games start taxing the power of 2 5870s in Crossfire it'd be pretty cheap to drop in a 3rd instead of replacing the pair of them with whatever the current gen would be.

So, to the OP: as I said earlier I'd feel more comfortable with the HX850.

To me: by the time you need to consider a 3rd graphics card a new PSU would be an investment for the next build anyway so it's a non-issue. I'll probably replace the case too, although I'd have no issue taking a dremel to what will be a 2-year old Raven to do a 3rd card mesh intake (I'm not cutting up a brand new one!)
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a c 248 ) Power supply
November 30, 2009 10:23:30 PM

Actually, we are going to seeing more energy efficient video cards that will require less power. We're already seeing that with the ATI Radeon HD 5000 series. This is just the start of things to come.

Starting about 4 or 5 years ago there was a big push in the commercial IT community to go green and reduce energy consumption. That's how the 80+ Organization got started with power supply testing and certifications 4 years ago. We're just now seeing the results filter down to the gaming community.

Manufacturers are working on reducing the dies for gpu's and cpu's from 40nm down to 32nm which will definitely reduce power requirements further. In addition they are working on embedding the gpu right into the cpu. It's quite possible it "might" mean the end of video cards.

Just thought I would throw that out there for what its worth.
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