Motherboard or graphics card problem

[Gracias]

When i try to start my computer, the power button gets switched off by itself.I had given my motherboard to the service centre and they repaired it. After that, I dont know why my monitor says "check signal cable" all the time. Still the issue is not solved...and i m worried if the motherboard is fine and the graphics card is the issue.
Mother board is MSI
And the graphics card is MSI R9 270X 2GB GAMING EDITION

 

[jasperhuang93]

What are the rest of the specs of the computer? Do the GPU fans spin up when you press power on the computer? Is the computer itself receiving power from the PSU? (case fans spinning up, lights coming on on the motherboard, etc). If the computer is shutting off by itself right after you power it up, it may be a power issue and not a GPU issue.