PC Upgrades. What should I use my money on?

[GreatFlashyGloop]

I built this computer over 2 years ago, with some of the parts almost 3 years old now, so it's safe to say it may be a little outdated.

 

I've recently been looking at getting a new case, gpu, and possibly processor. Here are my specs:

 

i5 4670k 3.4ghz

 

hyper 212 evo

 

evga gtx 660ti

 

16gb corsair vengeance ddr4

 

corsair carbide 300r

 

msi z87 g45 gaming

 

corsair cx650

 

 

 

What I'm looking to upgrade:

 

New graphics card (not terribly expensive, under $300)

 

New case (Preferably a windowed side panel, nothing fancy. Under $100)

 

Anything else that stands out as needing upgrading. I'm not very knowledgeable when it comes to things like this, so help would be awesome!

 

Thanks for taking an interest/helping me out!

 

 

 

 

 

 

[RangerLunis]

I got two things for you, a rx470, and the phanteks enthoo pro M Acrylic side window. 

 

Phanteks Enthoo Pro M Acrylic Side Window:  http://goo.gl/pxvVYA

Sapphire RX470 Nitro+:  http://goo.gl/ZB5mj8 

 

Bout $290~ all together.