Radeon HD 4650 fan problem

Hi everybody! Nowadays i've trouble with my ati's fan. It is making big noise. I thought i can get used, but negative. After a little time it comes like chinese torture.

I have tried everything (cleaning, oiling with appliance oil etc...) but the sound is only cut for a while. It starts making noise again and again.

So i have been planning to buy another fan convenient to Ati radeon hd 4650 (as you know fan is taking its energy from card itself).

Is the anyone knowing such a fan's traits (voltage etc..) which will be convenient to my video card.
 
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