Any had it when they are changing settings on the cards and the card starts doing 300kh/s and no matter what you change it too after it doesn't change from that .

EDIT:

OK i think thats because when sgminer crashes or the drive fails i hadn't restarted the computer each time.

Next question can you use TRIXX to change the gpu clock while sgminer is working, or do you need to restart sgminer to see if what you've changed makes a difference