Since it does only crash in heavy games but not under hashcat I assume a defect memory. Cause hascat uses only little memory and games use all they can grab. Just my 2cts.
But that card is technically worthless. If you do not buy it it goes to the trash or the seller might fraud someone to buy a broken card. You're his only option to make any money out of it. And for you 50€ spent are 50€ into the garbage, because you too will not be able to sell it later. It's a 50€ loss. The same loss you have if you buy a GTX1050 for 120 and sell it for 70 in two years.
So 20€ is my advice, 25 max.
But that card is technically worthless. If you do not buy it it goes to the trash or the seller might fraud someone to buy a broken card. You're his only option to make any money out of it. And for you 50€ spent are 50€ into the garbage, because you too will not be able to sell it later. It's a 50€ loss. The same loss you have if you buy a GTX1050 for 120 and sell it for 70 in two years.
So 20€ is my advice, 25 max.