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Is my psu good?

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August 1, 2011 4:20:01 PM

I have an ultra lsp550w. I use it on a gaming rig. I currently have 1 radeon 6850, and I may add another in the future to crossfire, but will my psu handle it?

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August 1, 2011 4:29:24 PM

if you plan to crossfire i'd recommend to you a corsair 750w or 850w would be great if you overclock your cpu or gpu
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a c 87 ) Power supply
a b 4 Gaming
August 1, 2011 5:50:36 PM

A good 550W PSU would be able to support two 6850s in Crossfire, as they are not particularly power hungry. However I'm not particularly convinced that the Ultra LSP550 is a particularly good 550W PSU.

You could give it a try and if you experience any problems then upgrade. 650W would be enough in that case, altho you could go higher if you want to cover more upgrade options down the road.
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August 1, 2011 5:54:23 PM

Silvune said:
A good 550W PSU would be able to support two 6850s in Crossfire, as they are not particularly power hungry. However I'm not particularly convinced that the Ultra LSP550 is a particularly good 550W PSU.

You could give it a try and if you experience any problems then upgrade. 650W would be enough in that case, altho you could go higher if you want to cover more upgrade options down the road.

Well this is my first build, and I don't want to already have to buy a new psu. Btw this is why I am in doubt, just look at the single xfx 6850 power usage: http://www.anandtech.com/show/4002/amd-radeon-hd-6850-o...
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a b ) Power supply
a b 4 Gaming
August 1, 2011 6:09:36 PM

That's why when you build a computer, you buy a psu that will be able to handle future upgrades, especially when your planning Xfire, which of course you were planning if you bought a Xfire capable motherboard.

Of course you failed to mention your other computer components or if your overclocking anything, so nobody can answer your question without guessing.
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a c 87 ) Power supply
a b 4 Gaming
August 1, 2011 6:16:41 PM

Firstly those numbers are for the whole system, and I'm pretty sure those numbers were taken at the wall. At full load a 6850 would draw around 130W. As power supplies are rated for the DC wattage they can provide you'd have to take 10-20% off those numbers to account for the efficiency of the power supply.

http://www.guru3d.com/article/radeon-hd-6850-6870-cross...
I use these numbers to get an idea of worst case power consumption numbers for people with one or two 6850s or 6870s. It will be worst case because they use a very power hungry i7-965. They show 393W at the wall, so a worst case actual system power consumption for them would be ~350W which only stresses a 550W PSU to ~64%.

Depending on what your CPU is I'm fairly certain that your maximum power consumption will lower than that, and even if it is as high, it will only ever be that high if/when you stress test by running programs like Furmark, which places an unrealistic load on a GPU. What CPU do you have btw?

64% wouldn't be stressful to a good 550W PSU, as long as it operating at/below it's temperature rating, as good PSUs are designed to provide their labeled wattage for extended periods of time - the only problem at 100% load should be fan noise.
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August 1, 2011 6:47:06 PM

http://www.jonnyguru.com/modules.php?name=NDFAQs&op=FAQ...

Use that calculator as it takes into account other things other calculators do not. Put it on 30% capacitor aging and 100% system load to be safe.

How efficient your PSU matters a lot and is rarely discussed. Get at least bronze certified PSUs..

I normally wouldn't stress my PSU over 40% for a couple of reasons:

1) Noise - It gets very noisy at over 50% for some PSUs
2) Capacitor aging



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a c 87 ) Power supply
a b 4 Gaming
August 1, 2011 6:52:33 PM

PSU efficiency is actually discussed quite often, for one JG reviews almost always mention efficiency, as do all other competent power supply reviews.

Capacitor aging becomes a factor after 10 years or so, or if the capacitors are not ventilated adequately, or are poor quality.
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August 1, 2011 6:56:43 PM

Better safe than sorry is my guideline. Not many people will take their PSU apart to check the capacitor quality and I keep my pc on 24/7 so you never know.

I very much disagree with many people here recommending 650W PSUs to run 560ti SLI setups....

Also, I don't know if the general questioner has even been to the jonnyguru site so I like to spread the info
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a b ) Power supply
August 1, 2011 7:09:37 PM

geis said:
I have an ultra lsp550w. I use it on a gaming rig. I currently have 1 radeon 6850, and I may add another in the future to crossfire, but will my psu handle it?


No, upgrade your psu as suggested, maybe something like this.

http://www.newegg.com/Product/Productcompare.aspx?Submi...|17-207-016^17-207-016-TS,17-139-021^17-139-021-TS,17-341-041^17-341-041-TS,17-139-010^17-139-010-TS,17-151-087^17-151-087-TS&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&AID=10446076&PID=3899435&SID=skim1402X558040X93866f82647ddc9002a13cf711afd862

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August 8, 2011 6:34:22 PM

Srry for not responding sooner guys, thats partly because my thread response thingy didnt update for some reason. Thnx for the info. I think ill stick with my psu, because im prob going to build a new computer in 4-5years, because that's how long they typically last, right (computers)? I have a 955, & yes, I am OCing
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November 22, 2012 4:25:04 AM

Best answer selected by geis.
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