What part to upgrade?

Below is a link to my current PC build. It is a couple years old and I would like to upgrade. What part should I upgrade to get the most significant performance boost for my money? I cannot upgrade the CPU without upgrading the motherboard as well.

http://pcpartpicker.com/p/FCVz23

You can’t upgrade macs.

For gpu rendering go with NVidia GPU instead of the Radeon

Please re-read the post, thanks.

Hi, I reread the post 3 times but don´t understand what you want.
Is the pcpartpicker collection what you have or what you want to buy, i think second.
If you want to go for CPU render buy Intel, a i7 4 core is already 30-100% (single core) faster than a AMD 8 core a i7 6 core much more.
If you want to go for GPU render buy a bigger card with 4-8 GB VRAM, you need a bigger power supply too.

Cheers, mib

The PC Part picker is my current build. I am asking what parts I should upgrade to get the most significant performance increase for my money.

From the PC Part picker list it looks like you could add an additional GPU to help your Cycles rendering. You might be able to keep your current AMD card and use it to run your monitors. Then get an Nvidia card like a 970 and plug it into one of your other PCIx slots. Your power supply might be able to handle a 970, but the AMD CPU and GPU are going to be pulling a lot of power, so to be safe I would up your power supply to 800W or so. If you go for a more powerful Nvidia card then you will definitely need to up the power supply.

Using both AMD and Nvidia cards together can work but YMMV, as I have seen cases where it works and others where it doesn’t.