I asked about this a year or two ago. It's on an ABIT IS7 motherboard. It has been making noises intermittently since then. It really slowed down today and making a whiny sound. So I took it off (ruined one of the three teeny screws). It has a unique clamping arrangement so there is nothing I can think of to replace it.
I ordered a new fan from ABIT, but I am wondering how critical this fan is. Should I take a chance powering it up until I get the new fan or not?