When to pronounce it dead

So when do you just pronounce it dead?

A desktop machine comes in and there's nothing on the screen. The standby light on the display doesn't even change color which tells me it doesn't sense that it's receiving a signal from the computer.

The fans start up. The hard drive spins up but I don't hear the head trying to access the drive to load the OS. I can hold the power button and the machine shuts down.

I've tried both the VGA and DVI video ports on two separate monitors. No response with either.
I've pulled RAM, one stick at a time until both were out hoping to maybe hear a beep. No beep.
I've swapped the power supply. Same symptom.
I've pulled optical drive and the only expansion card which was a wireless NIC. Same symptom.

At this point, it has to be either the board or CPU or both. The board looks nice. No bad looking caps. The machine is only 18 months old. This is a Power Spec B335 http://www.microcenter.com/product/459329/b335_desktop_computer

The CPU is a Pentium G4400.
The board is an ASRock H110M-HDV.

Any suggestions as to what else to try?

 

Check the CPU pins on the mobo, as well, Tony.
You never know, someone may have been playing, "Mr Fixit'
I would also unscrew the mobo off the risers, lift a little, and make sure nothing has fell behind the mobo, shorting out the board.

 

I'm inclined to repair it. The board is about $60 at Newegg. Problem I've always had is how do you know if it's the board or the CPU? I have some older P4 CPU which I know are good. Don't know if they'll fit on this board until I remove the current one.

 

I just tried (at your suggestion) a video card in a PCI Express 3 slot. No joy. Nothing on the screen.
The biggie is that I don't hear the hard drive trying to load the OS. It spins up, but that's it.

 

I hate it when that happens.