Hi!!!
I was looking for something associated with z590 aorus and I found your link! Well, ahaha you're going to laugh, but with what I see, my identification with the problem is EVIDENCE... I'll explain:
I have a gigabyte Z590 Aourus Ultra (almost the same as yours) and I had the geforce 980ti in the first slot and in the second slot dedicated to the second Graphics (here IS THE PROBLEM) the soundblaster z sound card... well it turned out that when I played the minutes the games closed for me! and it was due to a channel dedication problem, that is, this second slot does weird things with devices that are NOT graphics cards, since it hangs from the north chipset, that is, directly from the CPU and instead the other one that remains is pciex4 that hangs directly from the south bridge, my advice FORGET about this second slot and use the third slot to add your device as I did and no more hassle!!!
I await your news