4870x2 PSU requirement

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Mofofofo

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Geek

#91153 7-Oct-2011 14:11

Anyone have one of these cards? Just got one and I didn't think my PSU was powerful enough to drive it (550w) as the system didn't post, so I purchased an FSP Aurum 700w http://www.hardwaresecrets.com/article/FSP-Aurum-Gold-700-Power-Supply-Review/1228/7

That PSU has 4x12v rails which deliver at least 18a, two of those are video card ones so I put one each into the card which should theoretically give me 36a+ ?

Card still doesnt post though, has 3 leds on for a second then the fan slows to normal and the leds dissapear, which from searching the internet is the normal behavior?

Any suggestions?

timmmay

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#530701 7-Oct-2011 19:33

I typed a bigger reply but lost it. 550W PSU is massive, to reach 200W load you have to be doing something pretty crazy.

Does the system POST without the graphics card in? What about with a different card?

Mofofofo

41 posts

Geek

#530706 7-Oct-2011 19:58

After researching the subject I think the problem is that the powersupply's I have tried are divided by rails, eg 550w may be enough on paper but divided by say 2 rails, that means the card could only draw ~225w, potentially not enough for a 4870x2, the 700w is also divided into 4 rails so that may be the problem.

I'm going to try get a single rail power supply so the card can draw as much as it needs from the PSU.

timmmay

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#530715 7-Oct-2011 20:46

it really doesn't take 600W to post an idle video card. i think you're going down the wrong path.

Mofofofo

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Geek

#530742 7-Oct-2011 22:45

Yes I also had that thought, if anything I thought the card would at least post and if under-powered would crash in a game or at least when the drivers initialized.

I'm getting the PSU from the guy I got the card off that he had been using with the card. If that works i'll purchase it, if not refund.

timmmay

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#530753 7-Oct-2011 23:33

Same questions as before... does the system POST without the graphics card in? What about with a different card?

I really think you're wasting your time with the power thing. My old PC uses 100W under heavy load. If a video card used near 500W it would melt.

Try another graphics card.

Mofofofo

41 posts

Geek

#530754 7-Oct-2011 23:38

Yea I came from an 8800gt sli setup working fine with the 550, those are sold now however so I don't have a test card. Will test the post without videocard when I get home sunday.

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michaelt

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#530767 8-Oct-2011 01:48

I'm currently running two HD4850's with a 500W PSU.

I agree with what everyone else is saying. It should definitely boot with a 550W PSU, and the 700W PSU is overkill. If it doesn't, I'd strongly suspect a problem with the graphics card.

Mofofofo

41 posts

Geek

#534321 17-Oct-2011 15:17

Hmm seems you are all right about the PSU not being the issue.

My P5n-d just refuses to boot this card, I had 8800GT's SLI before the 4870x2 which worked fine, and now am running a 6600 while I decide on a new card, have no idea why it won't boot as I've found evidence suggesting others run a 4870x2 with this board just fine.

timmmay

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#534323 17-Oct-2011 15:19

Could be a faulty graphics card.

Mofofofo

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Geek

#534334 17-Oct-2011 15:50

Worked flawlessly in a mates PC for hours

powerforce

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#534352 17-Oct-2011 16:14

550w is pretty small for a 4870x2 and im confident its below the minimum reccomended.
They are very power hungry cards.
im currently running a 4870 crossfire setup with an 850w silverstone decathlon, its 70amps on the 12v rail i think.

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Mofofofo

41 posts

Geek

#534358 17-Oct-2011 16:32

The 750w single rail PSU I have now didn't launch the card so power isn't the problem. A 550w should at least provide enough power for post anyway

Things I've tried:
Cmos clear
Different PSU's 550w(Silverstone), 750w quad rail (FSP Aurum), and 750 single rail (TX750w)
Dip switch on the card that sets it to pci 1.0 rather than 2.0
Ensured all connections are correct
The other PCI-E slot
Ram sticks in different positions and individually.
One LCD in either DVI port

Lias

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#534362 17-Oct-2011 16:36

Tried flashing the latest bios?

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Mofofofo

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#534365 17-Oct-2011 16:39

Yep, latest bios.