Desktop computer - windows 10, does not boot

I have a desktop computer I made many years ago using an Asus motherboard M4A88T-M model using a using an AMD Athlon II 100 series processor. It has onboard graphics, as well as 2 superspeed USB ports, and quite a bit of DDR 3 memory.
About last June I shut it down, and moved it to another room while we did some redecorating in the room it was in. Now a couple days ago I plugged in the monitor to the extra video card I had installed in it, keyboard, and it's wireless mouse. Turned it on and nothing came up. Tried rebooting a few times with no success.
I turned off the monitor and back on when it was turned on. Monitor said no connection detected. So I turned it off. I had to use the power switch in the back as just holding in the power button would not turn it off. I moved the connection to the motherboard video outlet thinking that if it lost some CMOS info it might revert back to the default of that video . Monitor still said "No connection detected" when I turned it on .
Case side off and CPU fan runs as well as the exhaust fan on the chassis.

Any ideas?
I am now wondering if the CPU might be dead. When I turn on the desktop you don't even get the ASUS manager, and hitting "Delete" does not b ring up BIOS. In fact NOTHING comes up on the monitor when turned on, whether from onboard VGA or the VGA connected additional card.

When you work in IT it's common when you move a pc for this to happen reseat everything it's often a slight bending of mb that un settles something

CMOS battery perhaps?

dalchina said:

CMOS battery perhaps?

I thought that as well. Pulled out the battery and it was 2.9 V but replaced it with new, like style 2032 Lithium and still no booting. Battery would probably just loose the normal settings, but on turning on the computer, (Windows 10) Nothing comes up for CMOS or other.
Also I did pull out the video card when I was getting the CMOS battery out and then re-installed. You would think that the video, then , would be well. Might have to pull out the CPU and re-seat or perhaps I might have to buy a new CPU. Which begs another question. IF you don't have the CPU installed would it not beep at you in the beginning? And would the BIOS still start to show up?

Maybe resetting RAM, GPU and CPU will help if anyone is to come loose.

Hello @Gibbs,

As mentioned, moving a computer can have an affect on operations. Even the slightest bump or tilt can cause a problem.

It is best to just check that ALL connections are firmly seated.

I hope this helps.

Didn't see it mentioned but with custom/self-built computers most power supplies will have a switch on them near the cord socket. Also check that the red switch is set for 120V, not 220-250V.

Berton said:

Didn't see it mentioned but with custom/self-built computers most power supplies will have a switch on them near the cord socket. Also check that the red switch is set for 120V, not 220-250V.

If it's not the PS switch, try to remove the memory sticks, spray the contacts and the socket with a contact cleaner.

Now a couple days ago I plugged in the monitor to the extra video card I had installed in it

- that sounds like a change to the original configuration...