For about a year I've been running a Mythbuntu system as a stand-alone combo FE / BE on a Acer Aspire Revo 1600. (currently running version 10.10)
This system is completely silent.
There is a HDHomeRun dual ethernet tuner and an eSata 1TB drive attached.
While recording two programs and playing ATSC HD on this box even with the single core idle is still like 70%. (I avoid commflag)
Recently I decided to expand this system by adding a 2nd revo 1600 running minimyth which is pxe booting from the 1st revo.
This is working beautifully. Each is rated at 18 watts. Not sure how much power the 1TB drive is consuming.
Here is my FE / BE build which is attached out of sight up under the tv table.
The 2nd revo completes loading the rootfs in 18s from power up, and the mythtv menu is available about 60s after power up.
I may build a dedicate BE and change the combo FE/BE revo to a 2nd minimyth FE.
I am very impressed with the minimyth distribution. I just upgraded from 0.23.1-75 to -76 in just a few minutes and it works great.