What is gtx 420?

I'm sorry, but there is no such graphics card as GTX 420. The closest numerical model number to that is the Nvidia GeForce GT 420 which was released in 2011. The card is based on the Fermi architecture and has 48 CUDA cores, 1GB of GDDR3 memory and a 128-bit memory interface. It supports DirectX 11, OpenGL 4.1, and OpenCL 1.1 APIs and has a TDP of 50 watts. The card is mostly used in low-end systems for basic multimedia tasks and light gaming.