Typically when it gives one long beep and continues cycling through POST codes,this is a BOS related issue.  You will need to strip it down to 1 stick of ram, and keep testing slots until one will post all the way.  It may have errors but will show a screen and otherwise boot.  From here, do a BIOS update, as always it is recommended to do this by the ISO/Burnable CD method, or via a thumb drive.  After the BIOS flash you should be able to reinstall all the ram and function as intended.