My question about mining of coins

Hello all, happy to be here!
I have a question regarding my computer restarting, right after I start a batch script.
My computer has a 8-yr old MSI mobo, i7 proc, DDR3 RAM. I installed an AMD RX580 in it last week. Every time I start a batch script up, within 10 seconds, my computer restarts.
I originally started off with Windows 10 and had the problem. Then I tried Linux Mint 18.2, but ran into a different problem. Then went to Windows 7 Professional. Both Windows versions do the same thing.
The AMD software version I installed and is running now on the Win 7 machine is: 17.7.2.
If I run the following batch file for mining Myriad (XMY):
"sgminer --algorithm myriadcoin-groestl --no-extranonce -o stratum+tcp://myrgrs.suprnova.cc:2529 -u <user.worker> -p x", it works fine, BUT only mines at 600Kh/s.
If I run the following batch file for mining Myriad (XMY):
"sgminer --algorithm myriadcoin-groestl --no-extranonce -o stratum+tcp://myrgrs.suprnova.cc:2529 -u <user.worker> -p x -I 19 -w 64 -g 4", the computer will restart within 10 seconds.
I have also put in the lines above the commands:
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
But, those don't seem to help anything either.
Has anyone else run into this problem?
Is it that my mobo is too old?