Help! With weird boot problem

[pchronic]

One day when I went to boot my PC I encountered a problem. The power light turned on, all the fans spooled up, but there was no output to my display and my keyboard only turned on for a few seconds then went black (at least the backlighting did). When I pushed the power button again the PC immediately shut off, I didn't have to hold it down at all.
I immediately did the stuff all the forums say: tried each RAM stick separately, tried to boot with the GPU uninstalled, did a CMOS reset, I basically took it apart and put it together again. And it started! ONCE. I got it back to the desktop, did some web browsing, played a bit of Fallout 4, and then hit a solid blue screen freeze. And then it refused to start again. Every time the keyboard would flash on for a few seconds and then turn off, while all the fans kept spinning and the HDD spooled up.
So, I decided to replace the PSU (mostly because the motherboard was no longer widely available and anything else would have basically meant building a new system from scratch). I took the PC apart, installed the new PSU and reconnected everything. And it started right up! This time it started to the BIOS setup screen, so I clicked through and it finished booting to the desktop. Everything was peachy, I ran a few programs, watched some videos, played some games. No blue screen. I shut the PC down and then tried to start it up again. And it didn't work! Same problem. Is it the motherboard? I really hope its not the motherboard. I think its probably the motherboard.

System Specs:
i5 3350p
Radeon HD 7870 XT
ASRock z75 Pro3
Corsair Vengeance 2x4gb DDR3 1600
Seagate Barracuda 500 gb 7200 rpm SATA
Corsair CX500 500W 80+ Bronze
Windows 10

TL;DR: PC didn't boot, replaced PSU, booted once, now won't boot.

 

[Dave8671]

Hi

All the tests you performed how long did you test each ram stick for? Seems this issue is intermittent.

I generally test ram each stick of ram for about an hour. If the modo is functional throughout every test than i would really test the GPU and ram more closely.

You may be able to find another brand of motherboard to fix that cpu if thats the cause.

 

[pchronic]

The tricky part about testing other components is that the cpu doesn't have integrated graphics, so with the gpu removed I can't tell if the system is actually booting or if the fans are just spinning. One interesting thing I did notice is that if I start it up with the gpu removed the usb keyboard stays lit instead of flashing on and off. If this means that the system is starting up then I'm guessing the gpu is bad, although it is strange that it started and worked fine the first time after installing the new psu. Thanks for the answer, I'll keep plugging away!

 

[Dave8671]

Buy a new GPU and see if the issue still occurs. I found 3 motherboards that support that cpu in case its needed.

https://pcpartpicker.com/products/motherboard/?compatible_with=intel-cpu-bx80637i53350p#f=2,7&R=5,4&sort=name&page=2

Goog luck