Make a simple trick and you Will see is not a RMA Problem… put MEM -1000Mhz... I have Gigabyte too and the problem is the Thermal Pads are very poor.. you need to change them to be able to mine to +100Mhs...
https://ibb.co/5r2YrCZI add a picture mining with lolMiner with the Gigabyte 3080...
Didn't understand what you meant by put MEM -1000 Mhz and how you are managing 100 MH/S, Please elaborate.
The -1000Mhz was only to show you that you don't have a RMA, you have temp problems in the memory... and you will have it also with a new card, and also with another brands...
With the -1000Mhz the memory get less hot and i will be stable from the begining... of course you will get only +70Mhs but they will be stable... because there is memory trolling.
My photo is after the solution of the mem temps...