I just received this board, running it now with a Sempron 3400 SDD (64W).
Yes, you can undervolt (doing it now with CrystalCPUID, down to 0.8 offered, Sempron locks at 0.975V running stock speed). CnQ supported.
Yes, you can adjust multipliers and clock speed - I'll confirm later.
Yes, fan speed is supported, but only on 4 wire fans.
The Sempron stock heatsink has a 3 wire fan, so I can't adjust fan speed
With board on tabletop, temperature of core seems to be around 26C running 40% processor load at 1.0 V and 200MHz x 9, room temp around 20C, mobo temperature is reported as 28C.
In a case, with 20% processor load (MPEG decoding) for several hours at 1.0V , core is at 27-28C, mobo around 30C. This looks very promising to me - passive cooling is looking good.
Only one gotcha - I wanted to use my DVB-S TV card in this mobo, after all, it is aimed at the home theatre market. When I use the DVB-S on-board hardware MPEG decoder, it crashes the system, forces an instant reset and reboot. If I'm lucky. If not, the system hangs with no way to turn it off. I've been using this DVB-S card for years in a Gigabyte/Athlon with no problems, so I know it's not the card. After research, I found that nVidia have had this or a similar problem for YEARS - direct access to the video buffers seems to be a problem. I suggest you check compatibility with Abit or nVidia if you plan to use a TV card or similar hardware in your system. Luckily, I was able to set the DVB-S card into a "software decode" mode of operation which uses the Sempron to do the decode, hence the 20% load referred to above, otherwise, I'd be seeing 2-3% load.