Check the fuse or breaker. Reset or replace if needed.
Check that the power strip is properly conected to the wall outlet, and that it's wire is intact.
Check that the computer is correctly connected to the power strip, and that the power strip is in the ON position. Test if the power strip is realy ON with some other device, like a lamp or desk fan.
Make sure that the computer's power cord is intact and properly plugged in at both ends.
The switch on the power supply must be on the side with a bar "|", not the O.
Make sure that the power supply is correctly connected to the motherboard. It may need more than one connector, connect all needed connectors.
Make sure that the computer is not stuck in hybernate mode.
That's all I can think of at the moment. Some one else may shime in with some other hints...
Electro, March 2014