Our desktop computer is a real workhorse. From processing photos in Lightroom, drafting with Autocad and Rhinoceros (3D modelling) for me, and Diane sitting on it for 8 hours a day
Our old computer was a desktop I built, with a low power mobile CPU motherboard. It uses a dedicated 12V power supply. Even though it was as good as I could build 5 years ago, it was somewhat out of date. It used about 25 watts at idle (When the USB ports kept dropping out, and a complete reinstall of the operating system didn't cure a number of ailments, we figured it was time to drop some cash on a new one.) We're too dependent on it for income. This is the computer I bought:
Intel D54250WYKH - what a horrible name. It's a very small form factor computer; about 4" x 4" x 2" high. It has room inside for a mSATA SSD disk and an additional 2.5" laptop size drive.It uses a very low power Core i5 CPU but is plenty fast. It runs on 12V even though the input jack says 19V (you have to delve into Intel's specs to find out it's happy to run on 12V). It has a cousin without the H suffix that doesn't fit a 2.5" drive; your only option is a mSATA SSD. Ours has an internal SSD for the operating system and applications, and a external 2 TB 2.5" drive for data. The data disk is backed up to another 2 TB disk regularly.
A note about backups for cruisers: we have sometimes taken the trouble to send a hard disk of photos and documents back to my sister-in-law's house, where her garage stores 5 or 6 cardboard boxes of our really important junk. This way if we lose the boat, we don't lose all our photos.
Here's a review of this type of computer:
The power consumption is amazing: idle at 8.4 W, watching videos about 12 W. Even pushing it on benchmarks the power consumption is only about 20W.
To the computer you need to add memory, a monitor, keyboard, mouse and a hard drive, so it's not the cheapest option out there. Our monitor is a Samsung 21" LED illuminated monitor that draws about 1A @ 12V as well. So when watching a video for 2 hours, our total power draw is maybe 4 Amp.hours. For cruisers on a strict power budget this really helps. So far I am quite impressed with it. And it's small enough you can throw it into our Faraday cage quickly if a lightning storm threatens.