Thank's a lot for your support. Like I said I tested a LOT of different settings but I will not post all of them.
I already OC that card before with CGminer way higher.
I cant be more gentle than trying to increase clock by 10MHz
gpu3:
disabled: 0
# core_speed_0: 300
# core_speed_1: 600
core_speed_2: 735
# mem_speed_0: 300
# mem_speed_1: 300
# mem_speed_2: 300
# core_voltage_0: 1.125
# core_voltage_1: 1.125
# core_voltage_2: 1.125000
--[ Debug info for O/C on GPU 3 ]------------------------------------------------
GPU is enabled, overclocking is enabled
OC command - profile 2: DISPLAY=:0.0usr/local/bin/atitweak -P 2 -A 3 -e 735
Results:
Setting performance level 2 on adapter 3: engine clock 735MHz
ADL_Overdrive5_ODPerformanceLevels_Set failed.
I will try to focus only on this card by disconnecting all the others one. Maybe it's a wiring problem.