gpu reccommendation

My grandson, 11 years old , is just starting into computer games. He has a Dell Inspiron 537, I-5 quad, 3.4 Ghz. Looking for a video card to replace his Radeon 6450. Friend suggested a GTX 1050 TI with 4 GB. another suggested a Radeon G570. I known both are overkill for his existing desktop...