Maybe the fan has stopped altogether.
Taking your computer to the shop is expensive, and most just replace the power supply anyway.
Well, here's the quick fix that you can do with things you may already have - and WITHOUT screwdrivers!
Done right, the repair takes under a minute, and can increase the life of a fan by years.
First, let's look at these fans and how they work, and what makes them fail.
Step 1: Sleeve Bearing Fan
This is a typical sleeve bearing fan. The shaft fits very snug inside a "tube" or sleeve.
The shaft as it rotates glides inside the bearing on an extremely thin layer of lubricant.
The lubricant is held in by a rubber grommet (plug) under the sticker on the fan. Some don't even have the rubber grommet, and just the sticker holds the lubricant in.
The problem is, eventually this lubricant escapes, suffers viscosity breakdown, or just dries up. Please note that vegetable or olive oils will suffer viscosity breakdowns faster than oils that are meant to be lubricants.
If you have removed the power supply, opened it up, and removed the fan, you can oil it in this area, then put the grommet (if it exists) and sticker back in place.
But what if you don't want to go through all that work? There must be an easier way, right?
Step 2: Too Much Work!!!
On my system there's the motherboard connection, and then power for 2 case fans, 5 hard drives, 1 SSD drive, and 3 optical drives.
That's a lot of cabling to mess around with just for a fan fix, and then I'd have to make it all look this neat again after I put it back together.
There's GOT TO BE an easier way........
NOTE: If your fan looks like the one pictured here, you WILL need to take off the side panel and lay the PC on the other side, but the fix will still work. Unfortunately you may need a screwdriver to take off the side panel! LOL!
Step 3: The Quick Fix That Lasts
Motor oil is a bit thick for our needs, so only try that as a last resort.
First, let's see if your power supply qualifies for this fix.
Looking at the back of the power supply, see if there are 4 holes at the centre of where the fan mounts.
If they aren't there, this won't work.
Step 4: The Trick...
Now, going on about a 45 degree angle from one of the upper holes, punch the needle through the sticker and rubber grommet and squeeze in some oil.
If there is no rubber grommet, the oil may start to leak out the hole you just made...as soon as it does, remove the needle.
If there is a rubber grommet, just squeeze oil in and remove the syringe as you do so. The grommet will seal up as soon as the needle comes out.
Now power up the unit, and let the oil work its way into the bearing.
Fans with rubber grommets last years after doing this. Those without vary in how long they last afterwards - but hey, you can just do it again down the road!
If you can manage to get some tape over the hole you made, it'll last longer than if you don't.
If the fan is one that has completely seized up, you'll need to move the blades back and forth until the fan starts to spin on it's own. I find a Popsicle stick is good for this procedure.
That's it, you're done, and didn't need your tool box, and probably didn't break a sweat.
Best of all, you didn't have to buy a fan, or power supply, or take it to a shop or spend a ton of time ripping it apart.