PCI-e riser cable issue - 780i sli mobo

[HanzJager]

Hello everyone, I hope someone can lend a hand.  I am running an evga 780i sli mobo with three 5870's.  I was hoping to use riser cables to get the cards out of the case into an open air set up.  The problem is that the computer will only get passed the windows 7 logo if one riser is attached.  If more than one riser is used it gets to the windows logo screen then goes black.  Currently I have 2 cards attached to the mobo and one that I can use the risers on that is out of the case.

Does anyone have an idea on why I can't run more than one card with risers?  Thank you!

Setup:
1250w PSU
780i SLI mobo
1gb Ram
x3 5870's  (will run 4 cards if I can get risers to work!)

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[Dargo]

One thing to try is to look through this thread

https://bitcointalk.org/index.php?topic=37880.0

and see if there is any info on your mobo. Some mobos don't play nice with risers. Also, could you clarify what mobo you have - "780i sli" isn't enough.

[HanzJager]

Thanks I'll take a look at that thread.

Mobo:  EVGA 132-CK-NF78-A1 LGA 775 NVIDIA nForce 780i SLI ATX Intel Motherboard

[Dargo]

What kind of risers are you using x1? x16? And where did you get them. Sometimes the quality on these things is complete crap, so I would inspect them carefully for bad solder joints, shorts, etc. You can also check the risers by changing out each one on the card you have running on a riser. I assume you are just trying to run the risers out of the 3 x16 slots on your mobo, and if so it is puzzling that this doesn't work.

[HanzJager]

I'm using x16 risers.  I got them off Amazon for maybe $5 each... cheap ones I know.  The one card that I can run with risers I actually have 2 risers linked together from the board to card.  I have also tested all the risers with the one card set up and they all work.

I guess it's not a big deal, it works great the way it is now with the one card off the mobo but would have been nice to have them all on risers.  Still a little odd they don't work though.

[Dargo]

Yep its very weird. You lose some bandwidth with the x16 risers, but otherwise there shouldn't be any difference (assuming the risers are good). At this point I would probably try linux to see if this fixes the issue, but unless you already know your way around linux pretty well, this isn't worth the hassle.