You can use the 7+ GPU mod from lbr,
7xGPU + Windows // modding AMD video driver is the answer
https://bitcointalk.org/index.php?topic=712228.0
7xGPU + Windows // modding AMD video driver is the answer
https://bitcointalk.org/index.php?topic=712228.0
Cheers . It does work but my Mobo does not detect R9 290 anymore now. I will have to test it on another mobo hopefully it is not damaged although the fan is still spinning.
If you look at other devices in the device manager list, you might find your 290 there, and then update driver again.
290 does not show up on device manager anymore although i uninstalled all display drivers and refresh the device manager. I think 290 is damaged but I dont get any sounds or error when it is connected on mobo.
I do not know What might be the issue .