You need a proper cooler
So long as you don't do any 3d stuff, you MIGHT be able to get away with using it with the fan not working for a short period 'cos it wouldn't be that stressed and the arctic does have some sort of heatsink - a fan blowing on that would surely help.....but you wouldn't have got a 9800 in the first place if you were only doing 2d stuff, right? The reality is that I am guessing here, so it's all at your own risk
Thought about fitting the stock fan back on as a stopgap?