Question : Problem: PC won't boot

We have a Dell Optiplex GX280 PC which isn't powering up.

There is a light to the system board which I assumed meant that the PSU was OK.
We have swapped the system board and still the PC won't boot - what else could it be?

Answer : Problem: PC won't boot

A light on the system board does not necessarily mean a good power supply.

IS it powering up at all do you get any beeps ?

have you tried removing any extra devices such as CD & DVD drives leaving only the hard drive plugged in ?

Have you tried reseating the ram or swapping it ?

If when you press the power button nothing happens and you have changed the board and verified all connectors are correct then you can try disconnecting the power switch from the motherboard and reattaching it if it still does not power up when you press the button you may want to try swapping out the power switch with one from another gx280 if that does not work work then most likely your power supply is bad try swapping the power supply with another gx280