Wanted to share this with you guys.
My pc had been switching off at random times for no reason, for around 2 months. But never doing anything specific, so I couldnt eliminate the problem. I tried everything from removing non-essential components to opening the side panel (just in case it was overheating randomly).
Anyway so eventually....It switches off and does not switch back on. Then I see a little smoke coming from the power supply....AHHHH I unplug the power supply as fast as possible, but just before I pull out the plug, I see that the Power Supplies light is still on, so I buy another power supply.
So armed with my new power supply, I plug all components in. All components switch on for around half a second and then switches off again. So after trying this like 3 more times with components removed. I see smoke coming from one of the capacitors on the motherboard AHHHHHHHHH Pull power plug out.
So now my motherboard is stuffed....*sigh*...So I buy another motherboard. Now nothing switches on....at all.
After swapping out the graphics card for an older one I have that works. I figure out that the pc refuses to switch on with the original graphics card.....Luckily the graphics card is still under warranty, I take it back. It then proceeds to short circuit the testbed computer they have at the shop

.
So after around 2 weeks of taking things back and buying new things, I finally get everything back from warranty.
Things that blew:
Graphics Card.
Power Supply.
HDD.
DVD-ROM.
Motherboard.
So when your computer randomly switches off for no reason repeatedly, take notice.