Power Problem?
Mainboard has all powerconnectors and enough Power?
Try just one card or plug the one out wich is in the long slot.
Sometimes this is an issue with some boards.
Switch to GEN 1 in Bios
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I do not have the card so may be something is messed up with cuda?
The rig works just fine when i boot it into regular ubuntu on my harddrive, and all 7 cards are visible to nvidia-smi and claymore. So it’s not a hardware problem, it’s something with hiveos setup. I just burned the downloaded hiveos image into a flash and booted from usb, and the cards are not recognized by cuda drivers (i guess)