Computer won't start. CMOS reset ineffective. Windows 10

[WeirdoWithaCello]

tl;dr Computer won't turn on. Won't respond to CMOS reset. Motherboard considered dead for hours, then managed to boot once.

I'm using an ASUS Z9PE-D8 WS. Recently, over the past week and a half, I've been unable to wake the computer from sleep mode, for which I can't find a permanent solution. So, instead, I've been shutting down or resetting CMOS to wake from sleep.

My first time resetting, I removed the CMOS battery, then when I replaced it, unknowingly did so inverted (+ to -). Despite this, the computer booted. Ever since, I discovered the board's CMOS reset jumper, and have been using that, instead. However, more recently, it's needed CMOS reset to start up in the first place. When I try to start up, the power light goes on, but nothing happens.

Now, it seems to be stuck in this state, perpetually. If plugged in, the power button will light up, but nothing else. Pressing the button is fruitless, and CMOS resetting doesn't seem to work, anymore. We've tried removing the GPU, making sure all the connections are secure, and changing the CMOS battery (correctly-mounted, this time). The only time it's turned on so far, it was sitting for hours without power, durring which time I had removed a USB fob for a wireless mouse. I have yet to replicate this miraculous startup, and have no idea what to attribute this all to in the first place.

Specs:
Motherboard: ASUS Z9PE-D8 WS
CPU: Intel Xenon E5-2670 2.6GHz 8-Core (x2)
Memory: G.Skill Ripjaws X Series 8GB DDR3-2133 (x8)
Storage: Mushkin Reactor 1TH 2.5" SSD
GPU: EVGA GeForce GTX 980 TI 6GB Superclocked+ ACX 2.0+

 

[rocktalkrock]

Does this FAQ page help. https://www.asus.com/us/support/FAQ/1029953

Try booting with the fewer ram sticks, 1 if possible. Check page 2-13 in your manual. Also try moving your video card to a different x16 slot.

 

[WeirdoWithaCello]

edit: dust

edit 2: grammar

Update: One issue I forgot to mention is the frequent crashes in OS; almost always Critical Process Died. They're about as old as the computer, and I've done everything I can on the software level to resolve them. However, given their still-frequent occurrence, I'm wondering if they may be related to the problem at hand.

We (my tech-savvy neighbor and I) have come to the conclusion that overheating is a large--if not the main--contributing-factor; given that, if allowed to sit without power for some time, the computer will boot. If there is any potential-cause we're overlooking, please let me know.

I've since re-oriented the CPU fans to better dispel heat, and changed the BIOS to run all fans on max. After sitting for 6 hours (record time), there has yet to be a crash. I am still hesitant to try shutting down or sleep-mode (restarting works, though, for reasons unknown to me).

Again, this started up recently. If our heat theory is to be believed, could all this have been caused by dust?

 

[WeirdoWithaCello]

Also, when playing TItanfall 2, I've noticed frame-skips that increase over time. Not FPS drops: the corner-readout never dropped below 60. However, it still acted like it was lagging. Not sure what to make of that.