gta5 can I run

No
Not a chance your cpu will be fine but outher than that no.
need at least 4 gb of ram recomend 8 gb
and the gpu will not run it no chance to be able to play it your lookin at a £150 upgrade to the pc to play it at any decent rate i would recomend a gtx 960 for you.
 


Model number of the i7?

i7 is a tier of products that has been running back to 2008. There's a big difference between an i7-920 and an i7-4790k.

A 4790k actually has enough GPU on chip to run GTA V at low settings without a GPU.
 


Alright, so he without a question needs a new GPU, can't use the onboard one since he doesn't have a new generation i7.

The CPU itself is still pretty solid as a piece of processing power.

You'll need 4-8 GB of ram, and at minimum an AMD R7 250.