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Unstable performance with 2 RX480 4GB cards

Question asked by amdev on Apr 28, 2017
Latest reply on Apr 30, 2017 by amdev

I'm running a mining software with 2 identical cards. When only 1 card is connected to the motherboard, it's OK. But when I connect the second card this error starts to happen: the second card has a variable performance. It doesn't matter which card is connected to the first PCE-E slot and which to the second. If I swap them the result is the same. The second has significantly lower temperature and lower performance:


$ sensors


Adapter: PCI adapter

fan1:        2341 RPM

temp1:        +66.0°C  (crit =  +0.0°C, hyst =  +0.0°C)



Adapter: PCI adapter

fan1:         477 RPM

temp1:        +45.0°C  (crit =  +0.0°C, hyst =  +0.0°C)


Also it has undefined core clock and memory clock:

$ cat /sys/class/drm/card1/device/pp_dpm_mclk

0: 300Mhz

1: 1750Mhz


It shows a values without the asterisk sign, while the first card shows one:


$ cat /sys/class/drm/card0/device/pp_dpm_mclk

0: 300Mhz

1: 1750Mhz *


I tried the command but it didn't help:

echo 1 | sudo tee /sys/class/drm/card1/device/pp_dpm_mclk


I have the latest AMDGPU-PRO 17.10.414273 installed under Ubuntu 16.04:

$ uname -a

Linux uminer 4.4.0-72-generic #93-Ubuntu SMP Fri Mar 31 14:07:41 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux