So, lets start with the fact that the power supply you have is one of the top five WORST power supplies EVGA has ever sold. The others that suck badly are the N1, W1, B, B3 (Early multiple samples of the B3 blew up during Aris Mpitziopoulos (Electrical engineer and power supply tester for Tom's hardware, TechpowerUP and the founder of Cybenetics which is another power supply certification group) testing for reviews), BQ, BT and BR series models. All of those units, including your BR, are very poor quality and are known for having substantial problems especially when used in systems that have a discreet graphics card.
It would be highly recommendable for you to digest the information available at the following two links and then use that information to find a different, far more suitable power supply for your system. Keep in mind, this is THE most important component in the system because when it doesn't work right, anything or everything else might also not work right. And when it doesn't work at all, nothing works at all. Not to mention a poor quality power supply can destroy a motherboard or graphics card incrementally over time if it has poor voltage regulation or high ripple, which a lot of lower quality power supplies do.
Now, I'm not specifically saying that this IS FOR CERTAIN the problem you are having, but I AM saying that it's next to impossible to figure anything else out when you have a KNOWN problematic power supply installed in the system.
Below you will find MY standard list of recommended power supplies and beyond that this thread is intended as a landing place for questions or discussions regarding specific units, platforms or related PSU tech, all of which are all welcome to be discussed here. If it's related to power supplies...
forums.tomshardware.com
PSU Tier List 4.0 rev. 14.8 (outdated) Last Update: 12-07-2021 Legend : Gray - EoL/obsolete and/or otherwise not recommended for purchase. Green - small form-factor (gold and blue colors are disregarded due to scarcity of SFX PSUs) Gold - best units in the tier (includes requirements for blue...
forums.tomshardware.com
Next, "16GB of DDR4" does not tell us what model your memory kit is, or how many DIMMs are in the kit since that could be 2 x8GB or 4 x4GB or even 1 x16GB, nor does it tell us if the memory kit is even validated as being specifically compatible with your motherboard model. There is a reason why motherboard QVL lists and memory manufacturer's compatibility lists exist and that's to make sure that the memory kit you buy is validated for use with that board. There are far more things to consider than just "my board takes DDR4 so DDR4 should all work" because it doesn't work that way most of the time.
Also, I'd highy encourage you to update your BIOS to version F63b. You are MANY versions behind and there have been a heck of a lot of fixes incorporated into all those versions you do not have. You do not need to do each of them, you just need to update to version F63B or at the very least to version F62.