Telefunken TEL-73GIQ games crashing

Hi all, I bought a Telefunken tablet (TEL-73GIQ) and it said quad core and 1gb ram but when i try run my games like Gta Sa, Mortal Combat X and Gangstar vegas, it just crashes, the only one that works is Black Ops Zombies. I'd really like some help with this as I paid good money for this tablet