There are plenty of storefronts offering a GTA 5 download. However, Rockstar recommends that you stretch to 8GB of RAM and we recommended freeing up 72GB on an SSD. You'll also need 4GB of RAM and 72GB of storage space. Similarly, if you're still rocking a 13 year old Nvidia 9800 GT or AMD HD 4870, the gates of Los Santos will be open to you but stretching for an Nvidia GTX 660 or AMD HD 7870 will offer a much smoother and prettier experience.
That said, an Intel i5 3470 and AMD X8 FX-8350 are needed to meet the recommended system requirements. Gaming CPUs have come a long way but an Intel Core 2 Quad Q6600 and AMD Phenom 9850 from over 10 years ago still have the power to run GTA 5. Since GTA 5 first released on the Xbox 360 and PS3, the GTA 5 PC system requirements are extremely low.