I checked the user manual for the MB but did not see an onboard speaker that emits a single beep when POST has successfully completed, does your MB have an internal speaker and if so do you normally hear a single beep when POST completes but now you get nothing even with the Ram removed http://www.poweronselftest.com/
Before you replace the MB I suggest that you do a barebones set-up outside of the case, see canned text below;
Best couple of suggestions I can make would be first remove the MB and do a barebones set-up on a piece of cardboard (make sure it is larger than the MB) only connect the PSU, the GFX card (if present) the screen, 1 stick of Ram and the keyboard.
IF your MB doesn`t have a power test switch you will then need to short out the 2 power on pins on the MB header to get the PSU to activate, you can use a small flat bladed screwdriver or a paper clip bent into a U shape, this is perfectly safe if you do not touch anything else, the idea is to see if we can get a BIOS screen if you do you can then add one component at a time until you find the problem component, you must power down and remove the power cord from the wall before adding another component,
second suggestion try a known working PSU, it is not unknown for new components to be bad, third suggestion try and loan an ordinary PCI graphics card (not pci-e) again to try and get a BIOS screen.
Other things worth checking include, check for stray screws or bared wires that may cause a short, make sure the jumper cap that can be used for clearing the CMOS is not missing and make sure that the CPU fan connection is securely in place