There are CPUs pulling 140W at load, so your assumption of 100W for high end seems a bit underwelming. 100W would be a good rule of thumb for the old single core days or even dual cores, butthe quad cores definitely pull more.

I’ve used PC Power and Cooling’s ratings for a long time with great success. Your RAM estimation is much higher than their assessment. You claim 7W per 128MB. For a typical 4GB system, that would equal 224W. PC P&C recommends 15W per gig of memory, making a total of 60W needed for 4GB.

You list vid cards as 100W on the top end, but ATI’s HD4000 series is consistently pulling over 200W at load. In fact, the HD4870 pulls 283W at load.

The industry average on motherboard consumption seems to be going over the 50W mark while PC P&C estimates 50-150W. Again, that seems to be an overestimation on PC P&C’s part as mid-top end mobos are looking at 40-60W of consumption.

You also don’t bring up the fact that most people should budget overhead consumption into their totals. Most people I know budget for a 50% overhead, while I have seen as low as 30% overhead on top tier systems. I usually shoot for 40% as it’s a nice average overhead amount.

Lastly, you don’t mention power efficiency for load. PSUs are most reliable between 30-70% of maximum capacity.

I like the article, but I just wanted to raise these points as they kind of stood out to me.