Upgraded a pre-built, won't boot to post and no signal on monitor

[Genericcoyote]

Just upgraded my Prebuilt PC (imedia S2870) by moving it over to a corsair spec 03 and switching the power supply to a cx600w with a gtx760. Everything's connected to the micro atx board, but the monitor just won't display signal at all. We're not sure what the issue is, but if anyone has any ideas I'd be extremely greatful. Everything switches on and runs, the monitor just isn't picking it up. I've tried pulling out the ram and putting it back in, but to no avail. We think it might be the motherboard being incompatible perhaps? The motherboard is an acer H61h2-AD for any interested, there seems to be absolutely no information about it online. Any help at all would be amazing
It had a gt620 card which is too small to fit into the case. There is a VGA output on the motherboard but That doesn't work either it has the same problem when I remove the graphics card.
The onboard VGA has the same problem. I've disconnected and reconnected the lithium battery as well. Still won't connect to monitor





 

[axlrose]

Can I clear up, you are connecting via vga? The new gpu won't send a signal to the monitor? The onboard graphics won't send a signal to the monitor? The monitor itself is working?

 

[Genericcoyote]

The monitor is working yes but neither the onboard vga nor the gpu's DVI send a signal. The computer doesn't beep to signal that it has booted to post