thingieing :
everytime i shut down my desktop or there's a power outage (happens once in awhile), i won't be able to power the desktop back up, i gotta wait sometimes from 0.5-2.0 hr then it can be power back on.
after reading some stuff online, it narrowed down to either the motherboard or the psu? so what can it be?
You don't have an old power supply laying around you can swap in to check if it's the power supply?
I wouldn't rma my psu. If I was completely broke I would buy a cheap new one from best buy or somewhere, swap it out and find out for sure if it's the mb or psu. Then i would return the pse to best buy for a refund.
OF, course, when you can buy a brand new cooler master extreme power 500W psu from newegg today for 29.99 after rebate plus free shipping....just buy it. It will cost you half that much to ship your old one in anyway and it may not even be the problem so spend 15 to find out your psu isn't the problem and have nothing to show for it, or 30 bucks to find out and you have a spare psu going forward, or for you next build.
Just saved yourself three to four weeks without a computer while you wait to find out if it's the power supply or not too.
Also, have you tried resetting the motherboard after shutdown and see if it solves the problem? that would point to the motherboard, except it could still be a bad psu capacitors that causes the issue, so start by ruling out the psu.
Good luck.