You could try this, it won't take long and doesn't cost anything...
Unplug both power leads from the back of the PSU the one from the wall plug and the one going to the monitor from the back of your PSU.
While these leads are unplugged press the power on button on the front of your pc. This will get rid of any residual current left in any of the capacitors. Also press the on/off switch on your monitor.
Now plug in the power lead that runs between the back of the PSU and your monitor.
Then plug in the power lead that runs from the wall switch to your PSU.
Turn the power on at the wall switch and press the power on button, on the front of your PC.