In trying to build a silent HTPC after lightning killed my Biostar M7NCG, I've searched high and low for undervoltable micro atx socket 754 and 939 motherboards.
As far as I can tell the best bet seems to be either the
Jetway A200GDMS-Pro on socket 754
or the Jetway A210GDMS-Pro on socket 939
It appears that these boards support cpu voltage via the bios between 0.8v and 1.5v
If you are interested in the onboard X300 graphics the "pro" version indicates that the board has 32mb of dedicated video ram. As this is hardware DX9 it *should* be suitable for running windows MCE - but don't quote me on that!
Pair the 754 board with an E6 sempron (£45) or Turion or the 939 board with an £80 3000+ Venice chip and you should be able to build a powerful yet extremely cool PC.
It seems these boards are extremely hard to source in the uk at the moment, so finally having found somewhere that stocks them I figured i should share the information!
Both boards can be sourced from here:
http://www.mpcomp.co.uk/mpc.php?page=ca ... make_id=44
I have seen the 754 version slightly cheaper elsewhere but this is the only place i have found that does the A210gdms pro 939 board.
I also looked into running a Turion chip. These again are extremely hard to find in the uk, particularly the 25W version.
stock the MT30 (1.6ghz 1mb cache 22W) version which i figure would be the ideal chip for a passive machine. I hear people have been able to undervolt these to 1.0v (1.2v stock) and still overclock to 2ghz!
Last time i checked delivered price was £128
stock some of the other turions chips, but none of the 25W MT versions currently.
I haven't heard of anyone running a turion on the jetway board, but I am hoping that with the available vcore adjustment and overclocking options it should be possible to run the chip even if the bios doesn't recognise it.
I hope this has been useful, although please be aware that all of the information here is 2nd hand from forums etc and i can't verify it for accuracy.
If any of you have experience with any of the above kit or decide to go ahead and buy, i'd love to hear your experiences.