Pc won't start, help please

[Lesle87]

My computer will not start. It lights on for a 3 secs and turns off. I'm thinking I need a new PSU, not sure though. Because Theres a green light on my motherboard lit up and Ethernet light is lit up. Even after I try to start my pc up.

I have a corsair 750 watt psu (Almost 3 years old)
I game on this pc almost everyday. It was working fine last night, but now it's not doing so good. Help please, do I need a new psu?

 

[MeanMachine41]

Hi Lesle87 What tier rating is the PSU.?

The only way to determine 100% if it's the PSU (as the system won't boot) is to swap it out with another working unit of the same or higher Wattage.
3 years use is good if it's a bronze rated unit and a failing PSU can take other hardware with it so it definitely needs checking out.

 

[Lesle87]

This is the PSU I have Corsair CX Series, CX750, 750 Watt (750W) Power Supply, 80+ Bronze Certified https://www.amazon.com/dp/B008RJZQSW/ref=cm_sw_r_sms_c_api_W3QMybS20HNX6

It hasn't even been 3 years, I got and installed it in summer of 2014. I think there's a warranty for it, so I think I'll try to get a new one before it expires.

 

[Lesle87]

Can you still have a broken PSU even though there's a green light lit up on your motherboard?

 

[MeanMachine41]

Can you still have a broken PSU even though there's a green light lit up on your motherboard?

Yes you can Lesle87 and if you don't have the sophisticated testing equipment to test under load your only option is to swap the unit out. If it's still under Warranty then RMA the unit.

 

[Lesle87]

I bought a new PSU 850 watt corsair (Refurbished). Connected the motherboard and CPU then powered it up. Same problem happened. Pc only lit up for 5 secs then died again. What else could be causing this problem? Was I suppose to connect anything else to test?