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 
