I was sub-contracted to investigate and resolve a few issues for a large company.
One problem was in a training room with 8 PCs: but one pc had a very loud fan… loud enough that it caused a disruption to classes held in the room.
Before going onsite, I figured maybe it was a dodgy fan, or maybe an overheating CPU.
Once onsite, I could see the PC (a fairly recent IBM netvista) started normally and quietly, but after 10 or 15 seconds, a fan went into high-speed mode.
A peek inside the case showed that the CPU fan was spinning as fast as it could. Unplugging the fan stopped the noise… reconnect the fan, and it went back to full speed again. I started the bios setup screen, and before getting to the bios, I was given an “error 0135: fan failure” message.
OK, I borrowed and plugged in, a fan from another identical PC, but it also went to full speed.
This looks like a motherboard failure. I see if I can work around it somehow:
– there is a bios setting that controls the fan speed, but changing it has no effect.
– The fan cable has 4 pins, so I try popping out the 2 non-power pins (ie not the red and black), but it doesn’t slow down the fan.
At this stage, I give up and allow the support company to investigate if this can be repaired under warranty (otherwise a new motherboard will be needed).