Can I run gta5 and nfs rivals with my 1st generation i3 processor with 4gb ram

Solution
If you don't have a video card, a first gen i3 would be running GTA V at maybe 10 fps on low settings at 720 resolution if it even passes the compatibility check and installs.

Need full system specs, case size/brand/model, power supply brand and model, budget. You would want to double your RAM also to 8 GB for gaming.
If you don't have a video card, a first gen i3 would be running GTA V at maybe 10 fps on low settings at 720 resolution if it even passes the compatibility check and installs.

Need full system specs, case size/brand/model, power supply brand and model, budget. You would want to double your RAM also to 8 GB for gaming.
 
Solution
I've seen benchmarks showing stuttering issues on GTAV with 4gb, so I think for that game at least you'll want 8gb of system ram. For a graphics card, a GTX 950 is probably your best bet. Considering your CPU, there's not much point in spending more money on a more powerful card. This assumes you have an adequate power supply.

In terms of general performance, not gaming specific, an SSD does wonders to make an older system more responsive. If you don't have one yet, that should be on your list.