Symptoms of a faulty Motherboard?

[MassiveTurd]

Hello guys! Starting from the summer my computer has been acting weird and i decided that i couldn't deal with it anymore, and wanted advice from you guys to decide what part is faulty.

Computer Specs:
Windows 8.1
CPU - Intel i5 4570 3.2Ghz
MOBO - Asus H87M - Plus
Ram - 16GB of Corsair Vengeance LP
GPU - GeForce GTX 660 Direct CU II
PSU - 600W Silverstone
Running a SSD and HHD Combo

The Problem: So far from what i have observed the Computer will shutdown at a certain time and will not be able to reboot again until another time (generally tomorrow). For example i will be using the computer and it will shutdown and when i press the power button nothing happens, no fans, nothing. Now when it's the next day and i boot up the computer it's like nothing happened, if I was originally working on a word document and watching Netflix, then the computer turned off, when I turn on the computer in the morning everything would still be there, the word doc and Netflix. Also something to add when the computer automatically shuts down it will reboot by itself later and stay on this screen http://gyazo.com/c3698dc02465df187f54469452dba550. I have tried pressing enter to recover bios setting, but it doesn't work. I have to Press F1 go into bios and choose to boot into my SSD. Another thing to note is that when the computer boots up again, the time is messed up, i think the time starts from where it shutdown (as if nothing happened).

What I have tried: To this point in time i have tried booting with just the minimal requirements, one stick of ram, took out the GPU, and no harddrives, and the computer will still not be able to boot. I have also tried manually shorting the PWRSW but the computer would not boot. I tried the paperclip method to test the PSU and the fans did turn on.

I think this is a Motherboard problem, I feel as if the motherboard has a timer of some sort and the computer is able to boot within those times. What do you guys think is the problem, and is there anything I can do to with you guys come up with a diagnosis.

Thank you for reading this giant wall of text, hopefully you guys can join in and help solve this mystery!

 

[Alex Kiraly]

Does the computer randomly shut off completely? Like, *poof* and it's all turned off? Or does it go through the shutdown screen and all that? Does it act like going in sleep mode? It seems like a motherboard/psu problem. Did you try another PSU? Usually the first thing to debugging a problem is replacing things one by one. Eliminate all the causes to reach the problem. I suggest, try another PSU. Or if you can, another motherboard with the same psu you currently have.. Did you try clearing the CMOS?