Hello,

I've bought an old Asus P5K-V 775 motherboard with Xeon 771 modded processor (mobo BIOS modded to support it) and 8 GB RAM, which has 2x PCIe x16 slots. I have installed 2x RX580 and connected everything to 850W PSU (80 Gold efficiency). After that I installed Ubuntu Server 16.04 LTS and Radeon™ Software for Linux® Driver for Ubuntu 16.04.5 version 18.40. I'm using Claymore miner for ETC mining. After I have installed everything, I copied my config from previous machine which includes some limitations for fan speed, max gpu temperature, etc. I started the miner and soon noticed that second GPU (labeled as GPU1) is running at only 18MH/s, while the first one is at 28MH/s. The first GPU is physically installed above second and is being used as primary from the system itself (didn't change any BIOS setting, because the first time I tried to set to use IGD, I had to reset BIOS since it couldn't output image either to IGD or first GPU). It's a headless system. However, I'm a bit surprised that the problem arise on the second GPU, which is thermally in better position then the first one and one would expect that the first one would have more noticeable hash drop since it's used as primary graphics output from the system. I must emphasize that GPUs are not being throttled by the config settings in any case. I have tried different config values for miner, but there is no any way the hashrate of second GPU would change to it's expected value (somewhere around 25 to 30MH/s).

I have already searched for solutions from other people encountering the same problem, but seems I don't have the same problem as they had. Any idea/suggestion would be highly appreciated.

Thanks!