Help, new power supply won't start

[Jhow]

I just swapped power supplies for a more powerful one, I connected everything, press the power button and...NOTHING!

What should I try? What can I do? I've been checking connections but nothing is helping.

 

[G25r8cer]

Check if the switch is connected to the mobo and the wire is in good condition. Kinda a dumb question but make sure the switch is on in the back and make sure the voltage is set correctly. When i put my new psu i forgot to switch it on and was crapping my pants when it wouldnt turn on. I felt stupid and laughed

 

[Asiuweb]

I just swapped power supplies for a more powerful one, I connected everything, press the power button and...NOTHING!

What should I try? What can I do? I've been checking connections but nothing is helping.

Its your powesupply connector 20 or 24 pins,its your motherboard 20 or 24 pins,got it check that,or maybe you forgot to connect the 4 pin 12v connector

 

[Jhow]

The connector is 20 pins like the old psu. I checked to make sure it's switched on in the back. I tried just plugging it in to the motherboard and nothing else and still no power but when I put the old one back on the same way it worked fine. So I tried doing it on my older desktop (still same type atx). Same thing, nothing. I'm guessing it's a dead power supply.