Raske, try this, with amd driver 18-5-1 i never have problems, remember to put in ur walletadress and rigname and  adjust conf to as many cards u got in rig:
 i use this line in claymore:

setx GPU_FORCE_64BIT_PTR 0
setx GPU_MAX_HEAP_SIZE 100
setx GPU_USE_SYNC_OBJECTS 1
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_SINGLE_ALLOC_PERCENT 100
EthDcrMiner64.exe -epool eu1.ethermine.org:14444 -ewal xxxxxxxxxxxxxxxx.RX580_1st_rig -showdiff 1 -epsw x -asm 1 -estale 1 -mode 1 -minspeed -175 -ftime 10 -gser 2 -eres 2 -wd 1 -allpools 1 -tstop 70 -tt 63 -ttli 73 -fanmin 50 -dbg 1 -fanmax 100 -etha 0 -cclock 1200,1200,1200,1200,1200,1200 -mclock 2195,2195,2195,2195,2195,2195 -cvddc 850,850,850,850,850,850 -mvddc 900,900,900,900,900,900 -r 60

i never use afterburner or any such prog. but i use amd compute mode and all cards have 1click bios mod

hope its helpful B-)