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Enough Amperage for a 5970 + 5850

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July 24, 2010 11:12:01 AM

Hi all,

I have been running a HD5970 and a HD5850 in crossfire in an Alienware Aurora but whenever I run Furmark on any settings otehr than 800x600 0x MSAA, it just reboots instantly.

I do have problems when running Crysis warhead at maximum settings (Full HD, Enthusiast, 8XAA) but it crashes/hangs/reboots as soon as the level starts when the load on all three Graphic cards hit 90%-%100. I can only run it at 2XAA or sometime 4XAA.

I'm thinking it is the graphic cards but could it be possible that the drivers or Alienware Components may be the culprit?

Specs of Power supply:

5x 12v Rails with 18 amps per rail.

Maximum 825watt combined wattage on 12v Rails.

The other 50watt is for the 5.5/3.3v Rail.

Is 18amps per rail a bit low for a 5970 with/without the HD5850?

More about : amperage 5970 5850

a b ) Power supply
July 24, 2010 11:46:13 AM

The make and model of the PSU would help alot specs mean nothing if its a crappy unit.
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a c 139 ) Power supply
July 24, 2010 2:12:19 PM

Is this an Alienware 750W Continuous rating with 825W PEAK rating?
What does it say on the data label of your PSU?

Alienware NPS-750AB-1 B

How does your system run with just the HD 5970 installed? Or just the HD 5850?
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a c 144 ) Power supply
July 24, 2010 6:44:47 PM

WR2 said:
Is this an Alienware 750W Continuous rating with 825W PEAK rating?

FIFY :) 

Peak ratings are useless.
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a c 139 ) Power supply
July 24, 2010 6:53:38 PM

vTL123 said:
Maximum 825watt combined wattage on 12v Rails.

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a b ) Power supply
July 24, 2010 7:14:46 PM

it sounds like a lousy psu. especially cuz dell/alienware, along with all the other oems always use crappy units to keep costs down...
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a c 243 ) Power supply
July 25, 2010 1:00:01 AM

shovenose said:
it sounds like a lousy psu. especially cuz dell/alienware, along with all the other oems always use crappy units to keep costs down...

Dell has used a number of psu oem's over the years, quite a few being Newton/Delta's that, while not the highest quality, are pretty decent.
They use a lot of Hipro's now, I have no idea about their quality, but look at the bottom of the post to see the Silver and Bronze 80+ ratings.
Costs are kept down by the fact that they order them by the 1000's.


A typical 5 rail layout dedicates 2 rails to the pcie connectors, don't know if thats the case with the unit in the Aurora.
If the rail ratings are as specified the op would be pushing just beyond the 36 amp limit provided to the pcie connectors since the 5970 can use 25 amps by itself when running Furmark, and the 5850 will add another 12a or so.


http://www.80plus.org/manu/psu/psu_reports/SP454_DELL_H...(80+).pdf

http://www.80plus.org/manu/psu/psu_reports/SP609_DELL_N...

http://www.80plus.org/manu/psu/psu_reports/DELL_GM869_8...

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a c 91 ) Power supply
July 25, 2010 4:40:29 AM

This may go off topic but what sort of benefits (if any) are to be expected of a HD 5970 and a HD 5850 combination (strange IMO..).. Doesn't the 5850 hold the 5970 back from performing to its full potential..??
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July 25, 2010 5:10:33 AM

WR2 said:
Is this an Alienware 750W Continuous rating with 825W PEAK rating?
What does it say on the data label of your PSU?

Alienware NPS-750AB-1 B

How does your system run with just the HD 5970 installed? Or just the HD 5850?


Right now, it is running without the 5850 installed.

And the power supply is rated for 825watt maximum wattage, it also has the 80 plus silver certification. Doesn't say anything about the peak wattage, only maximum. Guess thats peak.
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July 25, 2010 5:14:27 AM

Emperus said:
This may go off topic but what sort of benefits (if any) are to be expected of a HD 5970 and a HD 5850 combination (strange IMO..).. Doesn't the 5850 hold the 5970 back from performing to its full potential..??


I didnt exactly know what to do with the 5850 after the alienware came so after finding out that it was compatible, I just plugged it straight in even though there wasn't very much airflow.
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July 25, 2010 8:38:52 AM

Best answer selected by vTL123.
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