I recently built a PC for heavy duty projects and GPU rendering. It's been a blast to work with. If you're curious about my experience as a long term Mac user now using a Windows PC check out my blog post here. Below is a list of all the parts used to build my PC.
The cutest little mini ITX case I've ever seen. Due to it's size I'm limited to one GPU but it is able to hold a full size card.
Because it's mini ITX I'm capped at 32GB.