Can't get my 280x going in desperate help bounty

[Bru]

I started mining ~2 weeks ago - so im newb, with a GB 280x on Linux Mint, using cryptobadger's guide. Everything went well, was mining with 730-750kh/s until i decided to buy a 2nd 280x (same gb model). My mobo is F2A88X-D3H, it has 2 pciex16 (one x16 one x8). With only one gpu everything works well (tested both cards). When I insert both, Xserver (donno what is this) wouldnt start, xinit/xstart wouldn't work, also tried latest AMD drivers.
Then I tried other OSes ,LM x64/x86, smos, xubuntu, windows xp. In xubuntu i somehow managed to get them going, cgminer was detecting them, but it i got 300-400 kh per card, and one gpu was staying at 37-38C, and the other at 80C, something tells my the 2nd card wasnt mining, although cgminer said it was. After I changed the driver and i was getting kernel panics at boot.

I now installed windows xp, tried diferent drivers (old and new,) installed sdk for xp with open cl, Catalyst only list one adapter, and cgminer/guiminer list none.

I really need some help, donno what else to do. I want to stay away from other windowses (only got licence for xp).

Other info: my psu is 750w bronze (pretty sure it can handle my system, maybe not at full load gpu, but i don't think it's the problem). In BIOS i got 2 options in regard to gpus : in gfx configuration , i got NB default or SB - something like that (northbridge/southbrindge) tried both settings. Also want to say that both cards are connected to my monitor (i dont have dummy plugs).

I think the problem is with the drivers, or with the mobo bios.. I may need a certain version of ati drivers, that is new enough to support 280x and old enogh to be stable on linux.

Im also new to this, and would require a noob guide on how to do things
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LE: Installing Linux Mint, I figured out something. The instalation wouldn't boot if the gpu is in the x8 pcie slot. So the problem is with this slot I think..

[SailZStarZ]

First thing I would do is flip the bios switches. I feel like i know the solution to this problem but cant quite put my finger on it.

[Parliament]

When I insert both, Xserver (donno what is this) wouldnt start, xinit/xstart wouldn't work,

What do you mean by "wouldn't start"? What's the error message?

Other info: my psu is 750w bronze

That won't handle both cards at full load, this review says 365W per card...

My mobo is F2A88X-D3H, it has 2 pciex16 (one x16 one x8)

The slots are railed together, meaning that when you plug something into the x8 slot, the x16 slot gets throttled down to x8. Your problem might have something to do with that (the cards don't like x8?).

Also, do you have the cards bridged together or no?

[dangerdave]

have you given bamt a try yet?
I found that bamt worked with my setup when windows didnt want to.

[bittick]

install win 7 x64 and ill help you out.
I have 3 rigs with some r9 280x

[skleven]

That won't handle both cards at full load, this review says 365W per card...

Ofcourse it will handle it. I`m running 3x 280X on a 850w Corsair. In that review, 365W is what the whole system pulls at max GPU load. A single 280X is around 250W.

[skleven]

I have the same motherboard, and i have no problems at all. The only difference is that i`m running windows7 and using the PCI-Ex16 and two of the x1.

[Bru]

Thanks for reply guys,

In regards to the PSU, it may not be enough for full load, but it's plenty if they running at let's say 20% (while booting). The thing is I coudn't make them work when I insert anything it the 8x slot all hell breaks lose. Kernels panic, cinnamon / x wont start.

@SailZStarZ
What bios switches ?
@skleven

I have the same motherboard, and i have no problems at all. The only difference is that i`m running windows7 and using the PCI-Ex16 and two of the x1.

That's what I was thinking to do next. Buy a 1x-16x riser and try the x1 slot. Can you tell me if your riser are powered ?

[skleven]

That's what I was thinking to do next. Buy a 1x-16x riser and try the x1 slot. Can you tell me if your riser are powered ?

You should always use powered risers if the mobo does not have a molex or pcie connector. My x1-X16 risers are powered, but not the 16X-16X riser.

[Bru]

Ok guys I just made it work  . But you know how it is.. you solve one problem and create another. I was curious to see if by connecting them with xfire cable would work, but just when i wanted to insert the xfire cable, I notice a small white switch on the gpus, so this was the switch SailZStarZ was talking about ( I tought u asked me to switch something in bios ). Anyway, switching this did the trick.

Now i got other problems : my kh/s is low . I`m getting now 600kh/s per card and it's getting lower and lower. And i used to get 745kh/s with 1 card in the good all` days . Also one of the card is running very hot, and the fan is always 90-100%. Got my mobo out from the PC, and added an external fan but it's still very hot. So I guess I still have to get a powered riser when i got the $$ . Oh and this time cinnamon crashed, but I dont mind.

This must be one of the ugliest 'rigs' from the internets :
http://i62.tinypic.com/mlh201.jpg