Question Mystery death

[Trackmeat]

I shut down my computer the other night like always and when I went to boot it up in the morning it would not go. The lights and fans turn on but it won't power the ubs devices and my monitor reads that the system is off.

 

[rgd1101]

full system spec? include make and model of the psu

 

[Trackmeat]

It's an oldie and up to yesterday was still a goodie.
AMD FX8300
GeForce gtx 960
Gigabyte GA-78LMT-USB3 mobo
16GB DDR3
PSU EVGA 600w 80 plus
I tried replacing the PSU with a Thermaltake 600w (p/n TR-600) and got the same result.
It's not a huge deal if it is dead as it has been on the chopping block for quite some time now, but I would still like to try to troubleshoot this.

 

[Grobe]

Also - please tell if you've noticed some change in the system lately, like being less stable, etc, etc (I don't know what you mean by "chopping block").

 

[Trackmeat]

Only thing I've noticed is it has gotten a bit slower lately. "Chopping block" means that I have been looking to replace it soon.