The fact you get VGA output/etc. and the system works means that it's not failing RAM. The system would beep one long beep and not
POST if it was the RAM. So whoever gave you that advice is barking up the wrong tree.
1. Have you contacted Supermicro Technical Support yet? If not, why not?
2. Are you using a Supermicro chassis? Does the chassis have have a SATA or SAS hot-swap backplane? If so, those can also have buzzers pertaining to overheating and fan status.
3. Any orange LEDs on the motherboard?
4. There's a jumper on the 4-pin SPKR header (sometimes labelled J9), across pins 3-4 (indicating to use the on-board buzzer). When the alarm is going off, try pulling the jumper off and/or putting it on pins 1-2 -- does the noise stop? If so, then yeah, it's the on-board buzzer/speaker which is making the noise. The only thing that ties in to that, that I know of, is the HWM/SuperIO chip.
I don't think Chassis Intrusion will cause this noise, but it might. Not 100% sure.
Anyway, if it's the HWM/SuperIO chip, then it might be failing or one of the related traces or components (there's usually resistors involved) has gone bad or is faulty -- this may happen so quick that the BIOS does not show it. Documentation says it's a Winbond (now known as Nuvoton) 83627DHG. I think this is one of those board models where the silkscreening + docs say one thing, but the actual chip operation is completely different.
5. One final thing to try would be flashing the BIOS (even to the same version). If it's the HWM/SuperIO chip, that may actually reset things to a default state (much more than "Load Factory Defaults" in BIOS), or may reset the HWM/SuperIO chip.
I'd recommend talking to Supermicro above all else though. Don't fear communicating with them, they're usually pretty good, just give them all the details and try to be precise/terse.--
Making life hard for others since 1977.
I speak for myself and not my employer/affiliates of my employer.