I recently purchased a new system with a ASRock A780GMH mobo and I'm currently getting no onboard video response, it's just a black screen saying check signal. I've tried both DVI and VGA outputs to no success. I'm using a 21.5" Samsung LCD and it works fine on this computer. My specs are as follows:
Hello, i was just browsing the forum and thought to register in order to help you.
I am afraid your motherboard is DOA (dead on arrival). I had the same with Asrock 780GXH/128M, which is practically the ATX version of yours (yours is the m-ATX). Fans were spinning, but no video signal. I even tried using a standalone video card, but to no avail. I RMA'd the motherboard through the reseller, got the replacement a few days ago (after about 25 days).