any idea, please?
No , but change your pool (look the efficiency)
go here :
http://xbit.nonce-pool.comEDIT : try it
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
sgminer.exe -k qubitcoin -o stratum+tcp://mine1.xbit.nonce-pool.com:4030 -u minerswing.1 -p 1 --no-submit-stale -I 18
I am getting : Share is above target?
You might need to put the flag " --difficulty-multiplier 256 ". Try g 2 or g 4. I am using g 4 on my 7970.
If you still have an issue, it might be the pool or try 512 instead of 256. Contact the pool to see if there an issue or mine at another pool.