I think you will find I was advising the OP similarly, instead of wasting his money on over spec'd parts.
However I do not believe the OP confirmed which fan he cleaned, and whether or not he opened the case, as no doubt the system will also be full of dust that requires cleaning, if not already done. You will no doubt know that the dust is being pulled into the system through the vents as the cooling fans extract the heat created, hence the need to clean.