are your "g" command set on 1 or 2? if it is 2 set it on 1
you will set the bat file with:
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
sgminer.exe -o stratum+tcp://xxxxxxxxx -u xxxxx -p xxxxx -I 13 -g 1 -w 256 --thread-concurrency 22528 --auto-fan --gpu-memclock 1500 --gpu-engine 1110 --gpu-powertune 20 --lookup-gap 2

before to start this setup, look on your sgminer or cgminer folder and delete the .bin files (like this: scrypt130511Thaitilg2tc20480w256l4.bin)

try several tc value, choice the highest your card start

dont forget that command "lookup-gap" is a comand who work with memory, so for high results, set it to 1.
if you undervolt your card and try to find best result saving more power possible, set lookup-gap 2

this setup is alredy overclocked, dont overclock over again.
how is voltage of card? stock voltage? or it is undervolted? use the software "gpu-z" for have it.