Monitor not working on tower but works on other towers.
I need help.
First, i haven't used my Computer about 1 year, and when i use it My Monitor no signal shows up and goes to sleep. I tried to do some testing and had 2 hp towers, 1 hp monitor/1 samsung monitor, 2 hp laptops/1 toshiba laptop. I hooked up both towers to a monitor, and no signal so i switched both monitors and still no signal. Then I hooked up all laptops to both monitors and it worked. When I hooked up the towers again still no signal.
Do you guys have any suggestions on how I can fix it?