How to check PSU without plugging in everything?

[COTTN]

So I recently got a replacement modular PSU and I want to check to make sure it works before completely removing my non-modular PSU and finding out my new unit is DOA and having to put my old one back in. Is there any way to do this?

 

[HillBillyAsian]

plug the 24 pin mobo and cpu power connectors in and fire it up and have it sit outside the case, if you get to the bios, then that much is working.