This is basically I think the very first product that features 7nm technology and it seems very buggy according to many people. This reminds me of the older AMD Fury/Nano GPUs that they released back in 2016 or so. I remember that a large percentage of those GPUs actually had lots of faults. The GPUs prior such as the Hawaii series or the Polaris series never had much issues.

Why did you buy the GPUs from an international marketplace? Usually in those scenarios whenever there is an issue its always difficult to get a refund. You probably can get warranty directly with the manufacture since you are the original purchaser and it might be cheaper than shipping it back to the store.