Here's where it comes down to numbers. We're going to assume that you intend to buy a workstation. The operative question here is, would it be better to buy a faster workstation or save money by purchasing a render node or two to run with it?
This CineBench test chart shows a fairly linear progression up the scale of processing power. Keep in mind that the bottom two processors show a sudden drop in xCPU scores (xCPU is when CineBench is running multi-threaded, while it runs as many threads as there are processor cores) because they are only dual-core CPUs. The information in this chart allows you to use simple math to see how much performance an extra node or two would offer.
Say your workstation is a Core i7-940-based machine, which turns a CineBench score of 14,544. For the price difference between that processor and the Core i7-965 Extreme, you can build an entire Core 2 Duo E7200 render node, which would give you a combined CineBench score of 19,762, far exceeding the performance of a Core i7-965. If you had a workstation using a Core i7-920 instead, the savings, when put in your render node, would allow you to build the node using a Core 2 Quad Q9550 and give you a combined CineBench score of 24,389, which is very close to doubling performance. Note: the ability to show combined performance by simply adding the CineBench scores is why it was used for this comparison.
The other performance advantage to having render nodes is that they can be rendering while you are working on your workstation, thus maintaining full interactivity and enabling you to use your processor's resources while the nodes are crunching away on a rendering task. For a complex project, this capability can become very important.
So there you have it, all the secrets to building your own render farm. Hopefully, many of you will be able to put this information to good use. While some specific elements of this article will be dated in six months, its general principles have been relevant for years and should continue to be useful. In the future, Tom's Hardware will look at workstations and test render nodes as well.