4 GPUs problem on x38/ich9r mobo

[twoBitBasher]

Hello,

I have got 3 5870s and a 5970

the first 5870 is connected to the first x16 slot and the 5970 to the second x16 slot which goes through the x38 chipset (pcie 2.0). No problems here.

the remaining two 5870s are connected via risers to the x1 and x16(x4) slots which goes through the ich9r.
My problem is that the card connected to the x1 slot crashes instantly when starting mining/connecting display to the card if the card on the x4 slot is connected. All the cards work rock solid otherwise. This happens regardless of the other cards being mined or standing still.
I tried also to set the x4 slot card to x1 mode by applying tape to the connectors but no change.

My mobo is the abit iX38 QuadGT, win 7, amd 12.1 drivers with v2.5 app sdk.

Any ideas on how to fix this?
This is clearly a driver issue as this setup works on BAMT also the 11.6 drivers don't crash the system if this x1 slot card is used.
Using the 11.6 drivers however is not a solution as I don't have enough displays/dummy plugs/resistors + the cpu bug is really killing my PSU and temps.

[twoBitBasher]

So which drivers do work / what work arounds have you guys used?
Please help!

[Kranke]

It could be an issue at the motherboard slot or at the riser itself. If you have other risers try those.

[twoBitBasher]

Now that is not the case... I said this setup works with the BAMT(Linux). Both risers have also been tested to work in their slots under windows. All cards work properly on the aforementioned 11.6 drivers under win7 one at a time(changing the display cable from card to card).

[nathantrumpet]

Have you tried downloading the most recent AMD driver 12.3? I started with 11.9 then recently switched to 12.3 and, at least with DiabloMiner, I do not have the CPU core utilization bug with a 5870 and a 5830. Also both cards are detected at Windows startup so there's no need for dummy plugs. If you give it a shot, I would completely uninstall your current driver version and the SDK. With 12.3 you don't need to download a separate SDK, just use the one included in the main installer. Good luck!! Let us know if you get it working.

[twoBitBasher]

Apparently nothing above 11.12 works so I went with that + 2.5 sdk, which gave a nice speed boost. cgminer 2.3.3 hangs on my 5970 second core(few hours stable) for some reason though it is completely stable on same frequency in phoenix(lot more cpu load ) and BAMT.

So it seems AMD sucks at testing their drivers properly before releasing them. Or they just like to force people to migrate to shiny new cards...