Which Linux OS on Athlon amd64, to comfortably run R?

Note that Ottorino has only 1GB of RAM installed, which makes a 64-bit
version of R somewhat moot.  See chapter 8 of

http://cran.r-project.org/doc/manuals/R-admin.html

Only somewhat. The Opteron actually has 1GB too (Hey, it was bought in
2004!  And the main point was to see whether 64 bit builds would work at
all) but 16GB of swap. So large data sets will fit but be processed slowly.

I would install a i386 version of R on x86_64 Linux unless I had 2Gb
or more of RAM.  I don't know how easily that works on Ubuntu these
days, but I would try it.

It's not like the 64 bit build feels slow for basic usage, though. I
don't think you need to bother with mixing architectures unless you have
applications where it really matters (CPU intensive, but below 32-bit
addressing limitations). Buying more RAM is much to be preferred.

Now what kind of RAM does my Opteron board take... ?

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