Mining ERGO (autolykos2) with two AMD RX560 2GB cards - second card has only half of the hashrate
When mining with two AMD RX560 2GB RAM cards inserted in full PCI slots, the second card has only half the hashrate.
OS: Ubuntu 20.04.2
Kernel: 5.11.0-40-generic

lspci:
```
09:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Baffin [Radeon RX 460/560D / Pro 450/455/460/555/555X/560/560X] (rev e5)
09:00.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Baffin HDMI/DP Audio [Radeon RX 550 640SP / RX 560/560X]
0a:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Baffin [Radeon RX 460/560D / Pro 450/455/460/555/555X/560/560X] (rev e5)
0a:00.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Baffin HDMI/DP Audio [Radeon RX 550 640SP / RX 560/560X]
```
nanominer:
```
Ergo: GPU 0 15.431 MH/s, GPU 1 7.449 MH/s
GPU0 t=68°C fan 35% power 27.11W, GPU1 t=61°C fan 18% power 23.24W. Total power: 50.35W
```
If I put the  third card to the PCI-E Riser (https://www.alibaba.com/product-detail/VER007-6pin-USB-riser-pci-e_60651057767.html) it does only 1,67 MH/s.