Hello,
I would suggest upgrading your PSU. The Ti4600 takes some power, give me a few minutes and I will have a wattage calc for you....Here is a list of some wattages:

https://forum.abit-usa.com/showthread...&threadid=2487

Here's the calculator:
https://www.jscustompcs.com/power_supply/

Hope this helps, the one other thing I would suggest, even though, you shouldn't do it if you play games also is upgrade to a 3d card, IE Quadro FireXGL, not nessicarly a gaming card like the geforce. And whatever you do don't get an abit Ti, and don't upgrade to a FX either, unless you plan on getting the 5950 Ultra, because the lowwer ones are slowwer than your Ti4600, trust me on this one. IF anything get a 9600Xt radeon from Asus, they are a pretty good card and have really good reviews. They out preform the 9800SE and non-pro.

As for the fan, if you feel up to it take it apart and clean it or just spray it with some canned air. Unless it makes a "noise" then you might need to oil it. The only thing with theses solutions is that it could quit on you at anytime. I would suggest a Thermaltake Volcano 11+ or 12. The thermaltake however are made more for the OC'ers.


Regrads,
Jklaroe