VFX render nodes

I'm looking to build a stack of 5 or 10 VFX render nodes as cheaply as possible. 

Been reading this:   http://www.tomshardware.com/reviews/render-farm-node,2340-3.html

But it seems quite outdated and was hoping to get some stronger CPUs on there + 8gb RAM

The recent $350 gaming build recently posted here got me thinking that I could use that AMD setup.

Would that AMD setup run on the 260w PSU in those enclosures?

Also - it's been a while for me and AMD, does AMD still run quite hot? Obviously this would be an issue in such a small space.

Lastly - The nodes will run linux - Can I boot and run Linux off a USB flash? That way I can further cut down costs by eliminating a physical drive.