No post after new CPU, now no post after reverting to old CPU? I'm at a complete loss..

[Captainzomb1e]

I'm at a completely dead end and hoping someone can help me please? I think it's the motherboard but wanted to check

 

Specs:

Old CPU: i3 4130

New CPU: i7 4790S

ASUS Z87-K - Latest bios

GTX 780 Ti

8GB DDR3, 240GB SSD.

 

On start up, the fans spin for 20s then stop, then start again and keep going but no post or display. The i3 was working fine, only when I switched to the 4790S did this problem start.

 

I tried a 4770K a few days ago, no display despite trying everything. I Went back to the i3 (working normally) and tried to upgrade today to a 4790S. The fans stop briefly then continue to go but there's no display, only two beeps with a long gap between them (could be post beeps?).

 

Now this problem persists with the i3 too, which was fine before.

 

I've done everything, different PSU and RAM, clear CMOS, latest bios version, only using core components (CPU, MOBO, RAM). It has to be the motherboard right? Thanks everyone