I gave my PC tower a blow out with some compressed air and now I'm noticing an annoying vibration sound any time it is idle.
Pushing on the CPU fan housing and heat sink have no effect on the noise, but applying some pressure on the centre of the fan itself stops the noise alltogether.
Does it need to be replaced or is there a fix?
Take it out of the CPU cooler and give it some WD-40 and put it back after drying. Next time, hold the fan blades before using the compressed air.
DO NOT use WD40.
Use powder graphite and remove any excess.
I use nonconductive silicon spray on CPU fans, looks similar to this
https://th.bing.com/th/id/OIP.CnSV1aRh1VrTS2DCB2Zl-gHaHa?pid…
except it comes with a tiny little tube you can attach to the nozzle to really get it into the fan motor housing. I give it a short blast which is borderline too much as you have to spin the fan to release excess of it and wipe it off with a cloth. Smells a bit when you first have it going in the PC again but that fades, can sometimes revive the fans that make a ton of noise. A lot of the time they will need replacement though due to age.
Did you allow the fans to rotate at very high rpms when using the compressed air ? You probably damaged it if you did. You need to make sure the fan doesn't spin when using compressed air.
Out/off balance.
You can try to gently apply pressure onto the centre of the fan (blade side) and see if it has a soft clip/sounds or the likes. Otherwise, try a very minor amount of graphite power as mentioned above. If no luck, good idea to replace it.
Similar problem to this? https://forums.tomshardware.com/threads/more-fan-noise-after…
If your CPU fan is old it might just have worn-out bearings, or maybe the bearings got worn out when you spun them at very high speeds with a air duster. If this is the case the fan will need replacing. You can't fix the fan's bearings.
If this is a stock cooler (Intel, AMD) I would replace the whole cooler, if this is a aftermarket tower cooler like a Hyper212, the fan itself can be replaced.