Quite possibly..A faulty PSU is probably the number one hardware problem in a PC..Unfortunately, in the wonderful world of electronics, sometimes the only to diagnose an intermittent (or otherwise) problem is to swap out the suspected part with a new/known-good part and hope for the best.

Personally, I would suspect the PSU and try another one..A faulty PSU would be the best-case scenario, as opposed to a motherboard.

Unplug and reseat all PSU connections first, though..May be an intermittent connection.

An EVGA SuperNova NEX750B should have a 5-year warranty.

Went out and bought a new PSU today.
Over the course of the last 2 weeks this has only happened 2 times (fans not coming on). The fans always start as soon as the power button is pressed. 
I've checked over the mobo and all the capacitors look fine. I've removed the CMOS, waited 1 minutes and and placed it back. I've also reseated all the plugs(?) on the PSU and the board. 
I'm installing the new PSU tomorrow AM. 
 
The EVGA PSU was bought in 2016 and past it's 5 year warranty by about 5 months. I'm not really certain what the lifespan of a PSU is. 

Well I'm still waiting for my replacement PSU to get here. I bought one from BestBuy and it was dead oob. Unfortunately it was the only one in stock so I had to order another which is expected either today or tomorrow. Currently the EVGA PSU is running in a test bench and there hasn't been a problem, but as I said previously it wasn't a constant issue. A buddy of mine checked out/tested my mobo and didn't see any issues with it.
Will update thread once the new PSU arrives. 

This issue sounds like it could be a power issue, but it could also be with something else... Try the new power supply, and if the issue goes away, the PSU was the culprit.

Otherwise I might suspect motherboard or something else.