Just built gigabyte 790fx xfx hd 5850 it boots up fine but no display, one beep

[Guest]

the whole system is new but the hdd is a week old running win 7 64 bit

 

[El Chupacabura]

The "One Beep" means the computer completes POST (Power On Self Test) which means that all of the low level hardware functions properly, so I would say it has to be a problem with the monitor or the cable from from your graphics card to the monitor.

Try swapping out the cable for another one if you have it and try connecting something else to the monitor to figure out if your monitor is shot.
good luck!

 

[vvhocare5]

Intel says 1 beep indicates a memory issue.

http://www.intel.com/support/motherboards/desktop/sb/cs-010249.htm

"You are getting 1, 2, or 3 beeps that indicate a memory failure.

1 beep - Refresh Error (with nothing on the screen and it is not a video problem) "

Have you reseated the memory and tried posting with one memory stick at a time?