Looking to upgrade my build.

When I was a freshman in high school, I built my first computer. My system specs are as follows:

• Intel Core i7 3770 (3.40 GHz)
• Nvidia GeForce GTX 660 (3GB)
• Crucial Ballistix Tactical LP 8GB Kit (2 x 4GB / DDR3-1600)
• Seagate Barracuda 1TB HDD
• Gigabyte Z77N-WiFi ITX Motherboard
• Antec 450W Power Supply

Now a freshman in college, I want to upgrade this thing. Looking back, I have no idea why I chose the parts I did, and why on earth I would put a 450W power supply in this thing. Before I proceed, I am looking for some opinions on what I should do.

I play a lot of games, and I would say that ArmA III is the most intensive on my system. I run a 1080p monitor, and want to be able to run it on Ultra and still get decent frame rates.

I am on a college budget, and am considering upgrading my GPU to the GTX 1070 and getting an SSD. If I do that though, will it be bottle-necked by my Ivy Bridge Processor and measly 8GB of DDR3 RAM? I assume I would need to get a new PSU as well.

Thanks!