When i pluged in my dell moniter my tower would turn it off or vise a versa?? no

[clueless_77]

when i pluged in my dell moniter my tower would turn it off or vise versa?? now we have checked all the plugs in the tower and when turn it on i get the disk boot failure insert system disk and press enter msg

 

[Ubrales]

You probably need to set the correct boot sequence. On Dell computers you need to repeatedly press the F2 key during boot.