I know this is a slightly different card (with a different HS), but I tested out my AIW 9000 Pro with a temperature gun and with the fan after running 3DMark for about 1/2 an hour it was 50C, then without the stock fan (and no other direct cooling except the case Panaflos running about 9V) it got to 63C and still climbing. No problems with running the software though, I just didn't want to test it to destruction!!!
So although that doesn't answer your question
I wouldn't just unplug the fan without some kind of direct airflow over the HS.