Well thing is if they boot up 5x other games and play each for an hour without crashing that is exactly what they are going to tell you.
Benchmark crashing is a concern I did not look into. The only time it ever happened to me it was a RAM issue (OC).
And just throwing it out there but all Rockstar PC ports give issues on PC without exception. They are not good porters. The fact that it takes them 2 years to port it should make you aware of that.
RD2 is known to crash on PC.
Just to be clear, I'm not telling you not to RMA it. I'm telling you to make sure its not the game instead of the card before you RMA it.