Hello. Gigabyte makes some fantastic products, but
you literally couldn't pay me to run a Gigabyte PSU in my own rig; especially that particular model. I admit that I do not know whether this specific power supply is the cause of your reported issue. But with all due respect, you've made the poor decision to purchase that power supply, and continuing to use it is an equally poor decision.
If I were in your situation, I would reach out to the retailer and request a return, then I would use that credit to purchase a higher quality unit. Normally when a return is granted, it must be shipped to the retailer at the customer's expense. But since problems with this specific manufacturer/model of power supply is well documented, perhaps you could convince them to allow the return while also supplying you with a shipping label that's paid at their own expense.
Regardless of whether or not you have the opportunity to return the power supply, there is absolutely no way that I would run that unit in my own system; not even if it were given to me for free. I agree with Eximo
that the Corsair RM850x is the minimum PSU that I would consider for a high-end Nvidia 30 series GPU. Just last month I gifted that exact same model to a friend who is only running a RTX 3060 Ti. Good luck.
: I apologize if my response above came across as rude; it was not my intention. I just have an affinity for PC hardware, and I get concerned when a part can potentially cause damage to all of the other components, or someone's home. If you have any further questions in this message thread, I promise that my future responses will be more constructive.