Trouble getting more than 2 radeon's on a motherboard to run

[beeph]

using the 890FXA lines from both biostar and MSI, and i always have trouble running more than 2.  I'm using either 4x5830's or 4x6870's in my setup.

The biostar has alternating pci16x 4x 16x 1x slots.  The 16x are red and the 4x,1x are white, the white slots are real close to the red slots so its impossible to put the cards side by side, so i use risers.

Everything is fine as long as im using one from the first 2 and one from the last 2, but when i try to put a gfx card in a red slot then one right next to it in the white slot (with a riser) it fails.

MSI has enough board space to allow all 4 to fit fine (jammed together but fits), but again same problem more than 2 and caput.

I'm using a 1080 watt Xforce power supply it has 4 12 volt rails with 20+amps on each rail, so should be ample power.

The funny thing is when i boot ubuntu on the biostar with more than 2, it frequently has weird behavior like artifacts, and the login window doesnt appear but the purple background does, etc etc.

Anyone have any ideas?

[1713858046]

1713858046

[1713858046]

1713858046

[1713858046]

1713858046

[1713858046]

1713858046

[namley]

I'm curious to the outcome,  I have 2 MSI mobo's with 4 6950's coming. I'll let you know how it goes.

[beeph]

namley i could NOT get ubuntu to boot on the MSI just FYI...

I'm NOT using dummy plugs on any of my cards, but linux does recognize 2 cards even without monitor switching.. Maybe dummy plugs would make all these problems go away?

[CydeWeys]

I have a similar issue.  I'm running a GIGABYTE GA-890FXA-UD5 ( http://www.newegg.com/Product/Product.aspx?Item=N82E16813128441 ) and I can't find any configuration of cards and risers that allows all four of them to work.  I'm stuck at three right now.  With three, the one that isn't working is the one that's plugged into the second x16 slot using an adapter cable.

[CydeWeys]

I'd really like to hear if anyone has gotten four GPUs working on a motherboard based on this chipset.  The four x16 PCIe connectors make it seem like it should be possible, but so far, it ain't working!

Would there be any possible issues arising from connecting a GPU to the motherboard in the x16 slot using a x16 to x1 adapter riser from Cablesaurus?  Would there be any point in buying just a standard x16 cable and use that instead?  The reason I have the x16-to-x1 is so I could potentially use the x1 PCIe slot on the mobo, but that didn't really work, and you'd think the x16 slot would work better ...

[Freakin]

it's probably not getting enough power on teh PCI-e bus.

Try splicing in a molex connector with an extension cable