Yes. 1 single, short beep means a POST successful beep, but only if that is the only beep you hear. Two short beeps, albeit spread apart by a couple of seconds; however, is not indicative of successful POST.
According to your manual, two short beeps indicates a CMOS Setting Error. Also according to your manual, the default display device is from a PCI slot (not to be confused with PCI-E). There are three types of display that is supported by your mobo:
"Init Display First
Specifies the first initiation of the monitor display from the installed PCI graphics card,
PCI Express graphics card, or the onboard VGA.
PCI Slot Sets the PCI graphics card as the first display. (Default)
OnChipVGA Sets the onboard VGA as the first display.
PEG Sets PCI Express graphics card as the first display."
-copied from page 38 in your manual
And here is where it get's complicated...
"Internal Graphics Mode
Auto Outputs from the onboard VGA if no PCI Express VGA card is installed. Always
outputs from the PCI Express VGA card when a PCI Express VGA card is
installed. (Default)
Disabled Always disables the onboard VGA, whether or not a PCI Express card is
installed."
- Also taken from page 38 of your manual.
So, by looking at your manual, and your confirmation of the two short beeps, I would venture to say you've got a deffective mobo. However, I would strongly consider installing a PCI-E video card and retest, just to make sure.
Another long shot would be to perform both methods of clearing CMOS:
1. Turn off power and then unplug 24-pin P1 connector and the CPU power connector.
2. Gently, remove the CMOS battery (looks like the size of nickel) for about a minute, or so.
3. Reinsert battery. Try to power up again. If still no display, try method 2.
Method 2:
1. Disconnect P1 and CPU power connectors.
2. Use your manual to locate the CMOS jumper/pins.
3. Move the jumper so that the opposite pin is now being jumped with the center pin.
4. Keep the new position for about 10-20 seconds, then return jumper to its original position.
5. Try booting up again. If still no display, I would seek an RMA.