I've wanted more RAM and a third monitor for a while. Upgrade time. I hate upgrading hardware, it's the worst of chores.
The new hardware is a Zotac Fusion ITX A motherboard including a Radeon 6310 graphics blah, a passive Radeon HD5450 graphics card (actually a 5430 chip), and the rest is from from the previous libertango: Silverstone SG05 case, Scythe Slip Stream 120mm fan, Be Quiet SFX power supply, SSD.
The difficult bit was to persuade Xorg (on Ubuntu Oneiric) to use
the graphics cards. It detected both graphics adapters, but didn't
pick anything close to reasonable settings by itself. I had to select
IGD as primary graphics device in the BIOS (the alternatives
NB PCIE and
SB PCIE, abbreviations make the world
go around) and then write some new files in xorg.conf.d.
The Xinerama option has to be on, GLX, Composite and XVideo must be disabled (otherwise VLC and Thunderbird crash the X server), the PCI IDs must be specified by hand, and when lspci says a PCI ID is 1:0.0, X wants to hear PCI:1:0:0. No leading zeroes, no dot. Type a dot, and Xorg breaks silently. One of the two graphics adapters must be specified by hand twice, one for each monitor.
Logging out and back in is not enough to test new X settings
in Ubuntu Oneiric, and
X :1 isn't really realistic. The right way is
to kill the X server process.
The resulting computer makes less noise than the Mac Mini I also have, and it's fast enough to work. But I have too many cables now.