Question Graphics card doesn't work, but when swapped it works?!

[Markspc]

SPECS:
CPU:Ryzen 1600 x
Motherboard:Gigabyte b450 DS3H
Graphics card:VEGA 64 Red devil
RAM 8GB

Games open up and get into the game then it crashes and brings me back to desktop, i had recently bought a VEGA 64 and it had been working for about 20 days then i played the new Call of duty which kept crashing but it was the only game that didn't work. One time it crashed and now all my games don't work i have reinstalled windows and still doesn't work, when i swap the VEGA out for my old RX 480 my games work fine. Also GTA 5 was the only game that works out of all my games. But now that doesn't work.
FIXES I HAVE TRIED:
-Reinstalled drivers countless times, also used DDU
-Diagnosed my RAM no problem there
-Reinstalled Windows COUNTless times

UPDATE: Most of my crashes now say Direct x error.

 

[tennis2]

Vega64 draws a lot more power than an RX480. What power supply do you have?

 

[Markspc]

Vega64 draws a lot more power than an RX480. What power supply do you have?

I have a 550 w Corsair silver + certified, But i don't think that is the problem, i had tried my friends VEGA 64 before buying my one and it worked perfectly fine, also my one had worked for almost a month until my game crashed.

 

[tennis2]

RMA then?

 

[Calvin7]

PowerColor Specs:
Minimum System Power requirement (W) 750 watts
https://www.powercolor.com/product?id=1511340918#spe
Your way off with a 550 watt Corsair.

 

[Markspc]

PowerColor Specs:
Minimum System Power requirement (W) 750 watts
https://www.powercolor.com/product?id=1511340918#spe
Your way off with a 550 watt Corsair.

As i already stated i had used my friends card, and i had already used this one for a month, so all together around 2 months of using the card, i don't think its the PSU or i would of had problems sooner.