PC wont post to BIOS

[Bam]

Stumped on this one.

I've been using a AMB1-ITX mobo and AMD 5350 setup but bought an upgraded CPU G4650 and H110i-Plus mobo and 710 GTX gfx card. Bits arrived on Monday so did the usual, power off, disconnect everything, then installed the minimal items, CPU, SSD (OS) and Gfx card\DDR4 compatible memory. I could not get a Bios screen. Spent a few hours checking and fiddling before resetting CMOS, still nothing. So at this point, swapped the old mobo and cpu (the cpu had not been removed from the old mobo) and the same issue, no BIOS post.

Chassis an CPU fans are on, and I can hears the additional HDDs spinning up, but just cannot get a BIOS post.
I've reset the CMOS on both (Pins and removing battery)
Changed display cables and tried all options (DVI, HDMI)
Checked the monitor is on auto or specified the connection
Checked the F_Panel pins on both and seem to have them correct, the Reset and Power work
PSU fan is on

Sadly the old case (Elite 130) does not have a speaker so cannot hear if there are any error beeps.

Any thoughts would be appreciated..

 

[Bam]

Resolved. IT Professional for twenty years did not connect the CPU 4 Pin. And I think the CPU may have been installed incorrectly. Doesn't explain why the old one would not boot, but now that boots as well. Part user error, part black magic.