Technical > Computer Hardware Help > Supermicro motherboard beeping

reply to n_w95482

Re: Supermicro motherboard beeping

OK- I'm learning something. Yesterday, I went to Best Buy and bought a Rocketfish 120mm PWM fan (the reviews on this have been mixed, but I can always take it back if the quality is junk). I just shut down the PC (there was no beeping) and replaced the Cooler Master Excaliber rear case fan with the Rocketfish. While things were apart, there was time for the system to cool down (not that it was very warm to begin with).

Immediately upon turning the system back on (before anything could heat up), there was beeping (sometimes the low-pitch beep, sometimes a low pitch which quickly changed to a high pitch). Changing the rear case fan to another motherboard connector had no effect. Looking in the BIOS Hardware Monitor, the Rocketfish seems to run about 100 RPM slower than the Excaliber.

So, it would seem that the beeping is somehow related to the motherboard detecting that the fan speed is slower than it would like to see- heat appears to have nothing to do with it. This would explain why disconnecting the case fan tachometer wire stopped the beeping- if the motherboard did not know that a fan was there, it wouldn't be checking to see if the speed is satisfactory.

As to why this condition has suddenly shown up, I have no clue. There is no place I can see in the BIOS to set a fan speed alarm threshold, so I guess that I will have to leave the case fan tachometer wire disconnected.

Yesterday, when the system was running (no beeps at the time), I used my finger to stop the rear case fan for a few seconds. Sure enough, the alternating high-pitch/low-pitch beeping started immediately. So, even though the Supermicro support rep swore up and down that this beep condition meant local overheating, it is definitely a fan-speed warning.

Perhaps on other Supermicro motherboards (or even on this one with a different version BIOS) the 2-tone beep signifies overheating, but not for my situation.