Thank you for all of you guys help. I did some more testing and have gotten different results. I am using a ASRock H110+ BTC Mobo, 8GB of RAM, and Intel Celeron CPU. I
-Made sure you have all the molex plugged into motherboard. 2 of them.
-Made sure the first gpu is in the long slot, the 16pin one
-I am using an Intel Celeron G3930 and have 8GB of RAM
I am also running HiveOS to mine for Ethereum.
I got the 3 RX5700 working. But for some reason, I cannot get any of the RX580 to work. I do not think its the risers because I swap them around and I still only get the RX5700 to work. So if I have the 3 RX5700 connected, and I connect one RX580. It does not show up on HiveOS, only the RX5700 do. Which if find strange. I can get the RX5700 working, but never 2 of the RX580. I can only get one RX580 to work if I unplug the rest of them.
-Switched all the PCI to gen 1
- 1st gpu should be in pcie 3.0 16 slot. Then the second goes to the black slot closest to cpu. Then fill up the black slots before using any of the white ones.
I have 2 power supplies. One 600W one for the MB and 2 580s and a 1200W server PSU for the rest of the cards. And I dont think its the mobo because its band new.
What I am trying to figure out now is why none of the RX580 work together.
Other things I tried
Things I tried.
-Enable 4G encode.
-Set PCIe support to Auto, Gen1, Gen2
-Enable/Disabled onboard graphics.
-Preferred Legacy boot mode
Here are some pictures of HiveOS and the BIOS. The red cards are the RX580. Doesnt matter if I switch them around or change the risers with the RX5700. The RX580 always show up red.