It doesn't matter what the TDP is. Home systems like HTPCs and home servers will run at their full power a very small amount of the time they're running. That means their maximum power usage (which is what TDP is supposed to indicate) does not matter.

Modern processors do some clever tricks to minimize using power if it is not needed, and have gotten progressively better at it. For home use cases, it's often worthwile to spend more money to get newer or otherwise more efficient PC components. This is especially true in areas where electricity costs are higher (e.g. average price per KWh can be almost twice as high in the Benelux when compared to the US).

One thing to get an indication about how good a CPU/chipset is is idle power usage of a system. It seems Ryzen is even better at this than Intel's already excellent Sky/Kaby Lake architectures [1], possibly because of the fact that Ryzen motherboards contain fewer components. On the contrary, the Ivy Bridge architecture of the chip mentioned by the parent cannot be considered competitive from a power consumption perspective, despite still being a great performer.

[1]: https://www.pcper.com/reviews/Processors/AMD-Ryzen-7-1800X-R...

The Ryzen 1700 has 8/16 and much better performance compared to the mentioned Xeon E3. I think the Ryzen 5's would be the ones to look out for (still more cores and much less price), hope they push the power consumption even lower.