I purchased a Biostar Viotech 3100+ as a low energy use mobo and noticed that the single core cpu is supposed to support the X86_64 instruction set.
http://en.wikipedia.org/wiki/VIA_Nano
None of the 64 bit, opensource OS's I have tried (Slackware 13.1, OpenBSD 4.9current, Arch Linux, NetBSD5,1 or Debian 6.0) are bootable and some (Slackware and Arch) return a message that the cpu is an i686.
The CMPXCHG8B instruction set is enabled in the bios.
I googled linux and openbsd in regard to the problem and searched the linux kernel bugzilla without any mention of 64 bit processing on this cpu.
I'm guessing it is either buggy and ignored or the issue has not been brought to the attention of the appropriate kernel coders.
Anyone have any insight into this? I'd like to report it as a bug but it looks like it would take the better part of the day to register at the various bugzilla's and mailing lists only to have someone tell me it is buggy and they are not going to address it.