Problem with GigabyteFXA-UD3 with 6 GPU`s and Linux Bamt

[VaporXY]

Hey guys

i  try to build a Mining Rig with a GigabyteFXA-UD3 mobo, sempron 145, 4 GB and 6 x R9 280x with 2 x 1x and 4 x 16x PCIe Extenders.

OS is Linux Bamt 1.2.

In the bios i turn all off. Only usb and lan controler are on.

If i start the Rig with 5 Gpu`s it run without problems. But if i start Bamt with 6 GPU`s the screen freezes when bamt is booting.

Has anybody an idea to fix this problem?

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[Flashman]

Might be a power issue, motherboards tend to have only about 200W of 12V available, idle power on those cards is gonna suck about 30W off the board each, plus what CPU and ancillary components use. If you have even one powered riser hanging around it might fix it...

There tends to be a tonne of variables in a situation like this though, kinda gotta rule things out one by one.

[VaporXY]

Thx for your reply.

I use 4 x 16x PCIe extender powered and 2 x 1x none powered. I think this is not the problem.

[Flashman]

Okay, take a look at how many PCIe channels the board provides and whether you are saturating them, considering the GPUs on the full length risers are only likely to drop to 8x

[VaporXY]

Product Specification (Manual)

2 x PCI Express x 16 slots running at 16x (PCIE16_1, PCIE16_2)
2 x PCI Express x 16 slotsrunning at 4x (PCIE4_1, PCIE4_2)
2 x PCI Express x 1 slots

Means that i have to use 2 x 16x, 2 x 4x and 2 x 1x PCIe extenders?

But if thats the reson why can i run 5 GPUs?

Do you think i can cut the 16x extenders to 16x?

[Flashman]

Ho hum this gets fun when they let the sales guys write the tech manuals...

According to this you've got 38 lanes total http://en.wikipedia.org/wiki/AMD_900_chipset_series

But then according to gigabyte product page, the full length slots run at 2x16 or 4x8...

Whatever, that's 32 accounted for. 6 left...  unless they do try to get 2x16 and 2x4 then we've hit 40... there's supposed to be an additional 4 lanes due to the northbridge, but I was getting the impression they were internal to the motherboard, for the gigabit LAN etc... if it uses one and leaves three, that's your 40, and one 1x slot working and that's it...

Well you can bug gigabyte on it, but they'll say it supports 4 GPU period.

[terminalc]

Try windows 8.1, at least then you'll know if its a hardware or software thing, then you can go back to bamt if you want.

I have 6 r9 290 running on that gigabyte mobo with 1x powered raisers if it helps.

[VaporXY]

Do you think i can cut 4 pcie 16x to 8x and use 2 x 1x.  8+8+8+8+1+1 lanes = 34?

OR will this mobo just run with 5 GPUs?