is the normal

yes ,I am the same with you
Well I'll give you some settings on 280X:
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
local path\sgminer.exe --algorithm bitblock -o stratum+tcp://maia.suprnova.cc:3453 -u **** -p **** --intensity 19 -g 2 -w 64 --gpu-platform 1 --gpu-memclock 1250 --gpu-engine 1100 --thread-concurrency 8192 --shaders 2048 --api-listen --api-port 4028 --api-allow W:127.0.0.1
pause