Need help!!! Motherboard is not Turning On

Disconnect power from the wall, press and hold the power button till all the lights
go out, then leave the system like this for an hour or so. If it still won't power
on you might want to look at trying another PSU, if the PSU has failed it may be
providing enough voltage to power the LEDs etc but not enough to power the system.

The paperclip test is useless. The PSU could be working well enough to run a fan
but not an entire system. It could also be functioning correctly for a particular
voltage but not others. Very few of the PSUs I have had die on me died completely,
they all would still turn on with a paper clip, sometimes even work on a smaller,
less power hungry system. The only way to rule out a bad PSU is to try with another
one.

Unfortunately PSUs rely heavily on capacitors to regulate voltage and voltage
ripple. Capacitors only have a certain number of power cycles in them before they
go bad. A bad capacitor can result in anything from a completely non functional
PSU to poor ripple correction. If the motherboard detects excessive power fluctuation
(ripple) it will not allow the system to power on (power protection).

All that said, if it's a good PSU it is fairly easy to revive these days simply
by recapping it or having it recapped for you. The better the quality of the caps
you use to recap it the better and longer the PSU will perform. I do this with
all my more expensive PSUs when they die these days, they make great backup and
test units.

Good luck

It's not a bad PSU, lower tier of a decent brand. Depending on PSU prices where
you are it may be worth getting recapped. Usually I only bother with 80+ Gold or
better rated PSUs but it very much depends on what's available where you live and
how much they cost.

Even a cheap PSU will be OK to test with, if the system powers back on again then
you can get your original PSU recapped and see if that fixes the issue. Do not
use the system with a cheap PSU full time however, cheap PSUs often blow spectacularly
and very frequently damage other components when they do.

Good luck