hello, i have an intel p4 2.4ghz with intel 845gvsr motherboard.from past few days my cpu fan is making very high noise like something is stuck in it but there is nothing touching the fan and there is no effect of this noise over my cpu speed.Is my cpu fan going to damage or it is normal.

Early warning to you...sounds like time to scare up a new fan Keep the old stuff running

Could be that the fan bearings are worn, and as LinoxOS2 has already pointed out, you may be in the market for a new fan. Don't forget, if this is the CPU fan, and you have to replace the entire heatsink/fan unit, you will have to clean the old thermal paste off the CPU itself and apply a fresh coat before attaching the new heatsink/fan to the CPU. 1 Corinthians 15:3-4

You might try "cleaning it" with compressed air but, as pointed out above, you should shop for a new HSF and make sure you install it with thermal paste.

Cpu fans often come attached to a heatsink as a package. If the cpu fan has compatible mounting screw hole positions and screw lengths, you may be able to remove the cpu fan from the new assembly and install it on your existing heatsink. Or - you could remove the fan and take it with you to where you buy another fan and get one that is exactly the same or has the same mounting screw position holes - smaller places that custom build computers and have a lot of parts are more likely to have the fan available separately. If you use the old heatsink, if it has mung on it, clean it before you install the new cpu fan. If you use the whole new assembly, they come with either thermal paste or thermal grease or have a very thin thermal pad attached to the bottom of the heatsink.