FrankyDeluxe

I just found the datasheet of my powersupply. http://www.recom.nl/data/rc-pe600cf.pdf
It has a triple 12V rail and a efficiency of 84%, so it's a pretty solid power supply. Any toughts?

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rx7racer

I would still test it. And I wonder what load they put on there to get the 84%. When a manufacturer places that on there they usually use a 50-60% load on the rails which is higher then common rigs will pull and get the effeciancy rating from it. So teh higher the load put on it the more ineffeciant it is.

So have you used a multi-meter yet out of curiousity. It is simple to do and would eliminate the issue coming from the most important part of a rig, which is your power supply.

And forgive me but I am not familier with Recom and can't find much on them, or at least I can't find anything I can understand.(looks like they have some nice products though)

grunion

The data sheet shows 440w max output on the +12v rails.

I'd say you're pretty close to that, if not exceeding it.

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Robilar

http://game.amd.com/us-en/crossfirex...nents.aspx?p=3

If you have a look at ATI's own certified list for HD4870's in crossfire, there is only 2 650W power supplies (an antec and a thermaltake) on the list. Everthing else is 750 watts and up.

Even though ATI specifies that the cards will run with a 600w power supply, they do not have anything less than a 650W on their own certified list?


The HD4870 is rated at 160w usage. double that for crossfire and you are at 320w. to Grunions point above, your 12v rails max out at 440W. Take away the 320w needed for video cards and that leaves you will only 100w on the 12v rail.

Have a look at the hardocp power tests:

http://enthusiast.hardocp.com/articl...50aHVzaWFzdA==

"Keep in mind that these wattages are taken at the wall for the entire system containing an Intel QX9770, 2GB Corsair, RAM, the video card(s), 3 WD Raptor Hard Drives, a DVD/CDRom, a floppy drive, and a Koolance Exos water cooling system. We used the new BFGTech ES-800 to power our systems. With that in mind, if you have an 80% efficient PSU, you can take the wall wattage and multiply by .8 to see what your PSU output would approximately be. So in the case of the 4870: 359w x .8 = 287w. This roughly shows that the PSU is actually outputting around 300 watts of power. (Keep in mind all power supplies are not built equal and many do not measure up to the rated wattage, especially nearing load. We highly suggest you check out our power supply section for reviews of solid units.)


All numbers above represent the same exact systems with simply a change in video cards. So you can see this hardly represents a "wimpy" system, although I am more than sure there are a few of you surpassing these numbers on your primary box. We used several different tools to load our GPUs, and in no way attempted to fully load our CPU. Given our methodology, GPU bottlenecking is our goal. We used FurMark, RTHDRIBL, Call of Juarez, and Lost Planets. Whichever could generate the biggest GPU power load was recorded. So in those terms the numbers are not apples to apples, but different configurations handled loads differently. There were some driver issues to skate around at this time as well, and the simple fact is that all of these numbers need to be redone in the near future when the driver sets have matured some."

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Chosen

http://www.firingsquad.com/hardware/...nce/page16.asp

(see power consumption)

I'm seeing 400w at full load for one 4870.

Nvm.

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Robilar

You have to factor that number times the efficiency percentage of your power supply.


Also, mate that is total system power consumption, not just the video card....

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Chosen

Whoops, my mistake

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liqwidstyx

as noted there is a good possibility your cards are not getting the necessary juice. try another PSU and if it fixes it great if not return it. Also i dont know alot about PSUs or electricity but I know that wattage is not as important as the amperage on your 12v rail.

FrankyDeluxe

Oke guys. Thanks a lot for all your quick input. Since i took the second card out today and everythings runs very well again (exept for Crysis), i'm RMAing my card today. Don't wanna blow another €100+ on a new PSU this month. I think i´ll wait a while till some new games come out, and buy one again, together with a 1KW PSU or so.

Still don´t think ATI played fair with recommending a 600W power supply for two 4870´s, while in reality this is far from realistic. Sure i'm not the only one who is making this misstake. When i say my car outputs 600HP, while it in fact only does 450, people call me a liar too...

Thanks again!

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RPIJG

Not all PSU's are the same though, and they can't be held to that requirement. Some PSU makers will tell you that they have a 800W PSU, but what they don't "say" is that there is maybe 300-400W on the non-12V rails (for a bad PSU maker). Or they use multi-rails as a means to really make it look like they have lots of watts, but not all of that is going to be useable to one source. It happens and AMD/ATI can't mandate that all PSU makers follow their requirements for a 600W PSU that will work with a 4870 in CF. Not to mention that temperature affects all of those readings. Alot of PSU makers will give you their ratings at something less than normal operating temperatures thereby making it look like it performs better than it will in the real world. Another factor that is always important to remember is that Watts is only half the equation, sometimes, it can be a problem with not having enough amps on the +12V rail.

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