If you bought that unit BEFORE 2014, then it was an "ok" unit, but is too old now to be trustworthy and/or is a prime candidate for age related failures.
If you bought it AFTER 2014, then it is not the same internally as what you saw in that Guru3d review. And, any review from Guru3d I'd take with a grain of salt anyhow because their reviews are not very in depth, unlike those like we are accustomed to seeing from Hardware secrets, HardOCP, Techspot, Tom's hardware and JonnyGuru.com.
Also, the ONLY review I see for a Rosewill Hive unit through Guru3d is for a 750w model, and it is VERY common for companies to offer anything from mildly to wildly different internals on units in the same series when comparing models with different capacities. A 550 or 650w unit for example, from any given series, might have a COMPLETELY different internal platform, build quality, and capacitor selection from another model, whether 450, 750, 850 or 1000w within the same series. A good example of this is the (now) older M12II 620w Seasonic units that are a solid but outdated group regulated design that lacks SOME modern protections, while the 750 and 850w models of that same M12II series are not group regulated and have a DC-DC design that does have one of the primary protections, Over temperature protection, that is missing from the lower capacity group regulated models.
Just about every PSU brand has something similar, and from one capacity to the next within the same series they may not even be manufactured by the same company. CWT might make the 450-650w models while FSP, Great wall or another manufacturer might make other models in the series. Very common. Just because one model in a series is good or even mediocre doesn't mean other models in the series aren't terrible, and that is in addition to changes to a series that might happen down the road as has been known to happen in both directions, good to bad and bad to better, such as with the Hive and with Thermaltake's TR2 units, just as examples.
SO, you might be right, that it was not originally a terrible unit if you know for certain it was purchased prior to the platform or manufacturer change, but if it was, then it is certainly much older than the point at which it was ever intended to continue running beyond. Which still, admittedly, doesn't necessarily mean that it IS to blame, but it certainly means that it would be a really good idea to replace it no mattter what.
The problem is, your board is likely at or near 7 years old also, and might definitely be a candidate for some age related failures, so I agree it can't be ruled out.
I think the only way you are going to positively identify which of these, or none, is the problem, is by replacing one of them. Unfortunately when it comes to motherboard failures there is really only one way to absolutely identify that it is to blame if there is no clear visual evidence that something is wrong with it, and that is to eliminate all other potential culprits. Swapping in a different power supply or a different graphics card are probably your only actual paths forward, and are not terribly helpful, I know, in helping to determine what is wrong without throwing some parts at it. If you have spare parts or somebody willing to loan you parts, that might be a really good first step.