do you have the hardware monitor installed? on my board, if a given voltage is close to the "warning" limit set in my hardware monitor, i will get an accasional chirp sound, which, in my case, was the error beep starting, but stopping before ht ewhole beep gets out. it was because of voltages fluctuating, and momentarily peaking over a set limit. my cure was to set that specific voltage's high limit to a higher setting, and in the case with my ddr voltage, 2.99 is the highest i could set it to, so, when i was testing ram at 3.05 vdimm, i disabled that specific reading within the hardware monitor.
this is just a guess, as you have a different board than i do, but still it's an abit. good luck.