I've got a P55 ftw 200 that's been working without issues for about nine years; it's a fairly lightly used system.  Suddenly it will no longer POST.  No video, no fans, no drive spin up, no beeps.  On the board itself, the red led in the center of the power button is lit, and the blue led labeled "led4" is lit.  Both are solid rather than blinking.  I don't see any other lights.  Going through cycles of pulling the CMOS battery, doing a CMOS reset, etc., have not changed anything.  
 
My first reaction is to say that the PSU has died.  It was new when it went into that system.  Does anyone have another suggestion?  I had another non-EVGA PSU go out on a Z370 a few months ago.  I hope I'm not at the leading edge of a streak of dying power supplies ....
 
Thanks for any help. 

rjohnson11,

Thanks for the suggestion.  All of my 24 pin PSUs are in use so I don't have one to test without major effort.  I'm doing a new system build and have a new (EVGA) PSU arriving Friday, so will test then and see what happens.  But, it sounds like your suspicion is the same as mine - PSU.
 
Thanks again.

rjohnson11, the new PSU arrived, and no change in symptoms.  (I made an error in my original description - I described the LED in the onboard power button as red; it's green.)

Cool GTX, I took your suggestion and stripped it down to just CPU and cooler and 1 RAM stick, and no change.  Even with the front panel connectors removed, and jumping the power pins on the board with a screwdriver, nothing. 
 
My experience is that with a properly working board but a bad CPU, there will still be other signs of life; if not fan spin up, at least beep codes, and I have none.  I hear a distant voice saying, "She's dead, Jim." 

Along with the new PSU, I got a Z370 Classified K and an i7-9900K, so as one dies, another is born. 
 
Thanks to both of you for your help.  I appreciate the time, and the suggestions were sound.

 

Cool GTX,
 
Yes, I swapped out the CMOS battery. I have enough old systems that I keep CR2032s on hand.  No joy.
 
Thanks.