Lately I notice a loud humming when first turning on my pc. Could this be a sign that one of the fans is wearing out?
Just for short time? It's quite normal that fans go full speed for short time when computer is powered on. That way it's ensured that fans start spinning.
One or two minutes. I just never heard it before lately and had the computer about 3 years. Iwas thinking a fan was wearing out.
Two minutes, that's quite long time then. It's also possible that fan causes case to resonate. Easy to check, when hearing that noise, put your hand on case. If noise is different, then it's probably resonation. If not, then probably fan is indeed getting broken.
It hasn't done it the last few times and I can feel coolness from the fans when I hold my hand over the vents. I have more than one fan.
Fan(s) may be a bit broken. Works fine some time, some time not so fine. Wait until that noise happens again and see what fan is noisy.