try to use --opencl -launch =768x8 and I get this errore the miner


VERSIONS: XMRig/2.6.1 libuv/1.8.0 OpenCL/2.0 gcc/5.4.0
* CPU: Intel(R) Pentium(R) CPU G4500 @ 3.50GHz x64 AES-NI
* ALGO: cryptonight, donate=1%
* POOL #1: cryptonightv7.usa.nicehash.com:3363
* COMMANDS: hashrate, pause, resume
[2018-06-23 18:43:00] compiling code and initializing GPUs. This will take a while...
[2018-06-23 18:43:00] Failed to start threads
Miner ended/crashed. Restarting miner in 10 seconds --------------

I am using xmrig-amd-v2.6.1