Desktop Won't Read Monitor

[cutiepatutie1388]

I have two old HP Pavilion desktops. I was trying to set both up and when I plug in the monitors it just stays black. Both monitors work with my laptop, so that's not the problem. I've tried switching them between both towers and that doesn't work either. Both monitors used to be hooked up to these computers a long time ago and used to work. Can anyone help? I don't know what to do.

 

[evongugg]

Clear the bios.

New build won't post checklist

http://www.tomshardware.com/forum/261145-31-build-post-checklist

 

[evongugg]

Are the fans and hard disks spinning?

You could have a dead power supply.

 

[cutiepatutie1388]

How do I reset the Bios? I had tried following hp's instructions but since I can't see anything on the screen I may have done it wrong.

And yes, the computers are both running, fans are spinning etc.

 

[evongugg]

The best way is to remove the battery for 30 seconds.

 

[cutiepatutie1388]

where is the battery? it's a desktop and runs off a power supply?
i've never taken a computer apart before.