So I have an ~2 years old Acer Nitro 5 AN515-52 (i7-8750h, GTX 1050Ti, 8GB RAM, 128GB SSD, 1TB HDD), and recently the fans have been making this weird noise. I don't know which fan it is, but I'm sure it's one/both of them. And it is definitely a recent development.
The noise is most apparent at about 2800 RPM. Anything well below 2400 sounds totally normal (can't hear anything unusual at 2100, for example), and anything above 4000 sounds pretty much normal (I guess the normal fan noise just masks the buzzing at those speeds). Close to the 2400 and 4000 numbers, you can still hear it if you sit in a very quiet room and concentrate though.
I haven't really been cleaning the thing regularly - I've only cleaned the dust twice (without opening the back-cover). I did that second cleaning today, and the noise has significantly reduced since. FYI I have also been working on it in a pretty dusty place for most of time I've had it - pollution levels are among the highest in the world, and there's quite a lot of dust in the air.
The fan speeds without too much load hadn't been too bad when I did the second cleaning though - 2400 tops while browsing/attending meetings. My estimate is that it would've been closer to 2000-2100 when it was brand new. The worst I've seen was touching 2600 while attending meetings. And it's back down to 2000-2100 now that I've done the second cleaning. The fan speeds have never been "unusual" under load either - never varied too much from back when it was brand new.
Thermals and performance have also always been great (I do run an under-volt of -140 mV on the cache, and -150 mV on the core). For the CPU, ~39 degrees on idle consistently ever since the UV, and almost always below 80 degrees while gaming, goes up to 85 under long-drawn heavy CPU load like long rendering cycles. Thermals have been REALLY good on the GPU as well.
Ambient room temperature: 25-28 degrees.
Sorry, I'm probably mentioning a lot of unnecessary details - just wanna put everything related out there, just in case it may be worth mentioning.
Can anyone take a shot at what the problem may be? Is it an obstruction problem? Should I open it up and take a look in that case? Or is it just a worn out bearing?
