What should be my next upgrade?

[P47Fighter]

Hello everyone, I'm relatively new to building computers, I built my first one about 3 weeks ago, here are the parts:
Intel G3258
Msi Gtx 750 ti
Asrock h81hd
Evga 500w 80 bronze plus
Mid case
8 ddr3 ram 4x2

Basically I want my rig to end up playing games at ultra with 4k that's my final goal, but I don't have the money to buy a i7 4930k 2x 780ti and all the rest all at once, I do have some extra cash now, and I would like buy a better CPU or motherboard or GPU to slowly upgrade my rig.
I would like to spend in one top of the line piece instead of upgrading multiple to the next available upgrade.

I was thinking maybe get a 780ti or maybe a i7 4790k or a motherboard, it could even be a new case so I can start fitting the new components there.

So what would you upgrade next and why?
Thank you very much for all your help

 

[manofchalk]

If you aspire to end up with a top of the line machine, buying a low end one with the intention of slowly upgrading isnt exactly the best way to achieve that goal.
To be honest, just sit on the computer you have and save your cash until you can buy a high end machine in one move.

 

[zeyuanfu]

Hello everyone, I'm relatively new to building computers, I built my first one about 3 weeks ago, here are the parts:
Intel G3258
Msi Gtx 750 ti
Asrock h81hd
Evga 500w 80 bronze plus
Mid case
8 ddr3 ram 4x2

Basically I want my rig to end up playing games at ultra with 4k that's my final goal, but I don't have the money to buy a i7 4930k 2x 780ti and all the rest all at once, I do have some extra cash now, and I would like buy a better CPU or motherboard or GPU to slowly upgrade my rig.
I would like to spend in one top of the line piece instead of upgrading multiple to the next available upgrade.

I was thinking maybe get a 780ti or maybe a i7 4790k or a motherboard, it could even be a new case so I can start fitting the new components there.

So what would you upgrade next and why?
Thank you very much for all your help

The mobo isn't important now, I would suggest the upgrade to the Core i5-4690K and maybe a 760/770? Post your budget and we'll figure something out.