Third card doesn't work

[mewantsbitcoins]

I am running Windows 7 32bit
Motherboard Gigabyte AM3 AMD 870 DDR3 ATX (SATA 6G/s USB 3.0)
I have 3 XFX 5870

The problem is that I can't get the third card to work. The two that are in pcie x16 slots are working fine. If I plug the third to pcie x1 via extender Windows doesn't recognize it. I've tried dummy plugs and even plugging in monitors, but still no luck.
However, if I take the two card from x16 slots and leave only the one in x1 it boots up fine and I can start mining on it.

What do you guys think could be the problem?

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[Meatball]

Possibly power?  Is the fan spinning on the card that won't run?  If not, you don't have enough juice running it.

What's your PSU for the setup?

[mewantsbitcoins]

I got 850W cooler master and read about guys running three card of 700W. Besides, it's the same if I put only one card in x16 and another in x1. The one in x16 works and the one in x1 doesn't. It seems that if there's a card in x16, my computer refuses to look in the x1 slot.
Fan is spinning

[Mapatti]

The PCIEX1_1 and PCIEX1_2 slots share bandwidth with the PCIEX4 slot. When PCIEX4 slot is populated with a x4 card, the PCIEX1_1 and PCIEX1_2 slots become unavailable.

Source:http://www.gigabyte.com/products/product-page.aspx?pid=3423#sp

[mewantsbitcoins]

That's bad news.
Mining doesn't require much bandwidth. Any way I could go around this restriction?

[alexdrans]

I am running Windows 7 32bit
Motherboard Gigabyte AM3 AMD 870 DDR3 ATX (SATA 6G/s USB 3.0)
I have 3 XFX 5870

The problem is that I can't get the third card to work. The two that are in pcie x16 slots are working fine. If I plug the third to pcie x1 via extender Windows doesn't recognize it. I've tried dummy plugs and even plugging in monitors, but still no luck.
However, if I take the two card from x16 slots and leave only the one in x1 it boots up fine and I can start mining on it.

What do you guys think could be the problem?

What're you buying from Overclockers for? You could have saved yourself £30-£45 by buying elsewhere.

[Genrobo]

It's probably a hardware level transistor that switches it off.
If it's software level, a modified BIOS might do the trick, but if it's board specific... Probably a hardware level transistor switch and you're SOL.

[Mapatti]

That's bad news.
Mining doesn't require much bandwidth. Any way I could go around this restriction?

Putting 2nd and 3rd card to PCIex1 slot might work.

[mewantsbitcoins]

That's bad news.
Mining doesn't require much bandwidth. Any way I could go around this restriction?

Putting 2nd and 3rd card to PCIex1 slot might work.

I was thinking exactly the same. Unfortunately I don't have another x16 -> x1 extender