Honestly, performance per watt is probably the least important consideration for a desktop computer.

Running a farm of these things? Maybe perf per watt makes sense to save some money. Mobile device running on battery? I totally get it.

But surely, the difference in cost for one person running it in their house, or a few hundred people in an office... like who cares? The cost savings won't even be noticeable on the power bill.

Performance per watt is also a good indicator of noise levels.