Well now.
Something failed to initialize.
First open the case check all the fans are spinning.
If one is not then it may be the cause, the mobo should be set to halt on all errors.
Meaning it will never fully post.
The message can also relate to a fact of no video connection found from the card to the monitor.
Some boards test for the cable connection via the video port and produce such a noise.
as no video cable connected, that may mean you have a loose connection on either end, and they are not in tight.
on the 15 pin Dsub/ Dvi/ Hdmi connector or display port connector.
This message will also happen if you have just built the system.
Pay attention here.
Placed a Pci-e card in the slot, but also have an integrated graphics solution on the mother board.
Also.
If it is the first time run of the system the video lead must be connected to the mobo video output port of the board.
Not the Pci-e based card or the second long beep will be herd.
You must do that, then enter the bios, and where it states the interface device or mode for the primary graphics card make sure the option is set to Pci-e if you do have a Pci-e card in the system.
Save the settings before you exit the bios.
Swap the cable from the monitor back to the video ports of Pci-e based card in slot.
And it should post without the second long beep and a picture on the monitor.
To me it`s a no signal cable error. cable not connected to set default video output port.