This is what Asus have released so far about AM3 boards and Thuban support; Ensure you've got the BIOS (number on the end) below to have a Thuban CPU![]()
Model Chipset BIOS Version
M4A89GTD PRO AMD® 890GX/SB850 1104
M4A89GTD Pro/USB3 AMD® 890GX/SB850 1104
Crosshair III Formula AMD® 790FX/SB750 1503
M4N72-E NVIDIA nForce® 750a SLI 2005
M4N82 DELUXE NVIDIA nForce® 980a SLI with NVIDIA NVCC and ESA support 1803
M4N75TD NVIDIA nForce® 750a SLI®Supports NVIDIA Clock Calibration(NVCC) function 0903
M4N98TD EVO NVIDIA nForce® 980a SLISupports NVIDIA Clock Calibration(NVCC) function 0603
M4A79 Deluxe AMD® 790FX/SB750 3204
M4A79T Deluxe AMD® 790FX/SB750 3004
M4A78T-E AMD® 790GX/SB750 3204
M4A78-E AMD® 790GX/SB750 2405
M4A78-E SE AMD® 790GX/SB750 1405
Just installed the 1104 BIOS today (which only just became available) pending my changeover to Thuban![]()
Just checked and my M4A785GTD-M is 6 core ready

Infact that list you have has been considerably updated

http://event.asus.com/mb/2010/m4_6cores/