If Fortnite is the only program that gives this error, it might be Fortite that is the problem. Or let the shop or Acer fix it under warranty.
Specs : -
Graphics Card: http://www.galax.com/jp/galax-geforce-gtx-1050-ti-exoc.html
Processor: https://www.amd.com/en/products/cpu/amd-ryzen-5-1600
Motherboard: https://www.gigabyte.com/Motherboard/GA-AX370-Gaming-K5-rev-1x
Power supply : https://www.amazon.in/ANTEC-VP550P-Computer-Supply-Continuous/dp/B00HEYWK76?tag=googinhydr18418-21&tag=googinkenshoo-21&ascsubtag=2a4f893b-386e-425e-a81a-ca03f56a060b
Ram : 8Gb ram 2666hz
Graphics card ; Galax gtx 1050Ti EXOC
Processor: Amd Ryzen 5 1600
Motherboard: Gigabyte arous x370 Gaming k5
Power supply: Antec 550W
Problem
So I bought my new PC with these specs and the starting month went Good I played JUST CAUSE 3 and TOMB RAIDER very well and Did some renders in Different video editing and 3D softwares
But a few weeks back I downloaded Fortnite and could play it for 20 -25 mins and the monitor displayed A blank color and the fans of PSU were running fast and the pc restarted after 5 mins
and now its happening even after just starting the game Fortnite , So i did a Stress test to GPU and it didn't go (FurMark and Heaven Benchmark ) well it did the same thing, but in CInebench the result was good for GTX 1050Ti (attaching the file) . So basically what is the problem ???????? GPU or PSU

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic