Tried with both script and sha - however cgminer doesnt seem to go above 64% gpu load. high intensity etc can "crash" or slow down pc but load is still pretty low.
for example:
cgminer -o stratum+tcp://x:3334 -u x.1 -p x -k poclbm -I 6 -w 256
it feels like wasting third of potential power.
increase your intensity, change the thread and you should be good..