Trouble shooting Help please new build problems

hi i have just put together a build with an asus sabertooth z77 and a intel i7-3770k with a xfx R7800 gpu on my frist start up it appears to be running the green on the mobo is on a small red light on the board where you plug in your devises is on but i get no boot up sound and i get nothing on my monitor so first i thought it might be the gpu so i took it out and used the on board hdmi but still no picture of boot up and asus logo please help me get this thing running i searched the forum and see where a couple of you guys have the same parts like Dee’s late build so i know someone out there can help me get started thanks for the help
sincerely lost: :

Pull the ram, and reinstall it one at a time.
Perhaps one of dimms is bad.

Also check that you haven’t got any cables stuck under the cpu heatsink. I saw that once. Lol.

If it isn’t the RAM, you might want to swap out PSU’s with a PSU that you know works and then try rebooting. Also make sure you have installed all the standoffs for the mobo and the backplate for the CPU heatsink. Look and see if the mobo is touching the case anywhere.