Continuous warble beep – boots OK

I have a Gigabyte GA-K8N51GMF-9 motherboard. The system was working fine until I moved it to another computer case. Now, although it boots OK, I’m writing this on it, the system beeps continuously. The beeping starts as soon as power is applied. It sounds like a European emergency vehicle.

The CPU is at 91F (Speedfan)and the CPU fan is spinning at 1900-2000 RPM (Zalman 9500)
I have reseated the RAM. The PSU is the same model and mfg unit from the other case (PC Power 520).
I tried it without the speaker connector from the front panel, but the system won’t start without it.

Pretty weird, eh?

John