I know you've dealt with a million problems like this, as I've sifted through them in an attempt to find a solution, but I've had no such luck as of yet.
Anyway, on to my problem;
Recently built a new rig (about a week and a half old now), and I've just installed some new case fans, as well as performing some cable management. Everything was working fine before this.
During cable management, I reseated my CPU Fan, in order to tidy the cable away as best I could. Now when I boot, I get CPU fan error.
What's strange though, is the fan spins up fine, and in BIOS it's shown as a CPU Opt Fan (even though it's definitely in the CPU Fan socket, not CPU Opt). The RPM looks fine too (around 1200, which is what it usually is, as far as I know). I've also checked the pins on the mobo, and none of them appear to be bent, as well as checking the wires' connection to the fan. All seems well.
Here's my specs (although I can't see why you'd need more than the mobo and CPU, I'll include it all, just to be sure ):
ASUS P8Z77-V Motherboard
Intel Core i5 3570k @ 3.4GHz with stock cooler
Corsair Vengeance 1866MHz RAM
GIGABYTE GTX550ti 1GB DDR5
Western Digital Caviar Green 1TB HDD @ 5400
Corsair TX650v2 PSU
4 CaseCom 120mm case fans.
Thanks in advance.
Edit; forgot to mention, I've been checking the CPU temps with SpeedFan and it's averaging at around 33C, so I wouldn't say there's any problem with the fan RPM (and like I said, BIOS said it was running at around 1200RPM anyway).
Well, I've plugged the cable back onto the same socket as before, and I never had any issues, however, I'll try swapping the cable on to the other socket again, just to be certain, but I'm 99% sure this won't change a thing.