Should I Upgrade so Soon?!

Ok so basically a little background, this is the pc I built in OCT of 2013 ( )
And I want to upgrade it to be super fast and I want to go with a custom loop. any suggestions and I will be changing the case to the FD Arc Xl. Should i upgrade so soon? What should I upgrade? Budget around 600$ (excluding custom loop)

get either an ssd, best bang for the buck in terms of performance.

or you can get  new motherboard/memory(faster memory) so you can overclock that cpu.

2x4GB ram sticks. 4Gb of ram which you currently have is cutting close to what most programs will use. Also, you could sell your 7870 and get a card from the 79** series, or get another 7870 and crossfire them. Personally, that's all I really think would be a reasonable change. 

Upgrade your RAM to at least 8GB

Add a SSD

Change your motherboard to a 990FXA Series 

oops forgot to say that I am getting another 7870 soon.