As per Asus themselves:
https://www.asus.com/Motherboards/M4A77/specifications/
140W CPU Support, so actually X6 processors are included:
CPU Validated since PCB Validated since BIOS Note
Athlon 64 LE-1660+ (DP),512K,rev.G2,45W,SocketAM2 2.00G 0301GO
Athlon 64 X2 5400+ (DO),1M,rev.G2,65W,SocketAM2 2.00G 0301GO
Athlon 64 X2 5400+ (DS),1M,rev.G2,65W,SocketAM2 2.00G 0301GO
Athlon 64 X2 5800+ (DO),2MB,rev.G2,SocketAM2 2.00G 0301GO
Athlon 64 X2 6500+ ,2.3GHz,1MB,rev.B3,AD6500WCJ2BGH,95W,SocketAM2 2.00G 0301GO
Athlon IIX2 215(ADX215OCK22GQ),2.7GHz,512KB,rev.C2,65W,SocketAM3 2.00G 0301GO
Athlon IIX2 225(ADX225OCK22GM),2.9GHz,512KB,rev.C3,65W,SocketAM3 ALL 2501GO
Athlon IIX2 235e(AD235EHDK23GQ),2.7GHz,1MB,rev.C2,45W,SocketAM3 2.00G 0301GO
Athlon IIX2 240(ADX240OCK23GQ),2.8GHz,1MB,rev.C2,65W,SocketAM3 2.00G 0301GO
Athlon IIX2 240e(AD240EHDK23GM),2.8GHz,1MB,rev.C3,45W,SocketAM3 ALL 0601GO
Athlon IIX2 240e(AD240EHDK23GQ),2.8GHz,1MB,rev.C2,45W,SocketAM3 2.00G 0301GO
Athlon IIX2 245(ADX245OCK23GM),2.9GHz,1MB,rev.C2,65W,SocketAM3 ALL 0404GO
Athlon IIX2 245(ADX245OCK23GQ),2.9GHz,1MB,rev.C2,65W,SocketAM3 2.00G 0301GO
Athlon IIX2 245e(AD245EHDK23GM),2.9GHz,1MB,rev.C3,45W,SocketAM3 ALL 0601GO
Athlon IIX2 250(ADX250OCK23GM),3.0GHz,1MB,rev.C3,65W,SocketAM3 ALL 0404GO
Athlon IIX2 250(ADX250OCK23GQ),3.0GHz,1MB,rev.C2,65W,SocketAM3 2.00G 0301GO
Athlon IIX2 250e(AD250EHDK23GM),3.0GHz,1MB,rev.C3,45W,SocketAM3 ALL 0601GO
Athlon IIX2 255(ADX255OCK23GM),3.1GHz,512KB,rev.C3,65W,SocketAM3 ALL 0404GO
Athlon IIX2 255(ADX255OCK23GQ),3.1GHz,1MB,rev.C2,65W,SocketAM3 ALL 0301GO
Athlon IIX2 260(ADX260OCK23GM),3.2GHz,1MB,rev.C3,65W,SocketAM3 ALL 2005GO
Athlon IIX2 265(ADX265OCK23GM),3.3GHz,1MB,rev.C3,65W,SocketAM3 ALL 2501GO
Athlon IIX2 270(ADX270OCK23GM),3.4GHz,1MB,rev.C3,65W,SocketAM3 ALL 2501GO
Athlon IIX3 400e(AD400EHDK32GI),2.2GHz,512KB,rev.C2,45W,SocketAM3 2.00G 0301GO
Athlon IIX3 405e(AD405EHDK32GI),2.3GHz,512KB,rev.C2,45W,SocketAM3 2.00G 0301GO
Athlon IIX3 405e(AD405EHDK32GM),2.3GHz,512KB,rev.C3,45W,SocketAM3 ALL 0404GO
Athlon IIX3 420e(AD420EHDK32GM),2.6GHz,512KB,rev.C3,45W,SocketAM3 ALL 2501GO
Athlon IIX3 425( ADX425WFK32GI),2.7GHz,512KB,rev.C2,95W,SocketAM3 2.00G 0301GO
Athlon IIX3 435( ADX435WFK32GI),2.9GHz,512KB,rev.C2,95W,SocketAM3 2.00G 0301GO
Athlon IIX3 435( ADX435WFK32GM),2.9GHz,512KB,rev.C3,95W,SocketAM3 ALL 0404GO
Athlon IIX3 440( ADX440WFK32GM),3.0GHz,512KB,rev.C3,95W,SocketAM3 ALL 0404GO
Athlon IIX3 445( ADX445WFK32GM),3.1GHz,512KB,rev.C3,95W,SocketAM3 ALL 0404GO
Athlon IIX3 450(ADX450WFK32GM),3.2GHz,512KB,rev.C3,95W,SocketAM3 ALL 2501GO
Athlon IIX3 455(ADX455WFK32GM),3.3GHz,512KB,rev.C3,95W,SocketAM3 ALL 2501GO
Athlon IIX4 600e(AD600EHDK42GI),2.2GHz,512KB,rev.C2,45W,SocketAM3 2.00G 0301GO
Athlon IIX4 605e(AD605EHDK42GI),2.3GHz,512KB,rev.C2,45W,SocketAM3 2.00G 0301GO
Athlon IIX4 605e(AD605EHDK42GM),2.3GHz,512KB,rev.C3,45W,SocketAM3 ALL 0404GO
Athlon IIX4 610e(AD610EHDK42GM),2.4GHz,512KB,rev.C3,45W,SocketAM3 ALL 0601GO
Athlon IIX4 615e(AD615EHDK42GM),2.5GHz,512KB,rev.C3,45W,SocketAM3 ALL 2501GO
Athlon IIX4 620(ADX620WFK42GI),2.6GHz,512KB,rev.C2,95W,SocketAM3 2.00G 0301GO
Athlon IIX4 630(ADX630WFK42GI),2.8GHz,512KB,rev.C3,95W,SocketAM3 2.00G 0301GO
Athlon IIX4 630(ADX630WFK42GM),2.8GHz,512KB,rev.C3,95W,SocketAM3 ALL 0404GO
Athlon IIX4 635(ADX635WFK42GM),2.9GHz,512KB,rev.C3,95W,SocketAM3 ALL 0404GO
Athlon IIX4 640(ADX640WFK42GM),3.0GHz,512KB,rev.C3,95W,SocketAM3 ALL 0404GO
Athlon IIX4 645(ADX645WFK42GM),3.1GHz,512KB,rev.C3,95W,SocketAM3 ALL 2501GO
Athlon IIX4 650(ADX650WFK42GM),3.2GHz,512KB,rev.C3,95W,SocketAM3 ALL 2501GO
Athlon X2 4850e (DO),1M,rev.G2,45W,SocketAM2 2.00G 0301GO
Athlon X2 5000+ (DU),1MB,rev.G2,65W,SocketAM2 2.00G 0301GO
Athlon X2 5000+(GI),2.2GHz,1MB,rev.C2,65W,AD5000ODJ22GI,SocketAM2+ 2.00G 0301GO
Athlon X2 5000+(GI),2.2GHz,1MB,rev.C2,65W,AD5000OGJ22GI,SocketAM2+ ALL 0302GO
Athlon X2 7450+ ,2.4GHz,2MB,rev.B3,AD7450WCJ2BGH,95W,SocketAM2+ 2.00G 0301GO
Athlon X2 7550+ ,2.5GHz,2MB,rev.B3,AD7550WCJ2BGH,95W,SocketAM2+ 2.00G 0301GO
Athlon X2 7750+ ,2.7GHz,2MB,rev.B3,AD7750WCJ2BGH,95W,SocketAM2+ 2.00G 0301GO
Athlon X2 7750+ ,2.7GHz,2MB,rev.B3,AD775ZWCJ2BGH,95W,SocketAM2+ 2.00G 0301GO
Athlon X2 7850+ ,2.8GHz,2MB,rev.B3,AD785ZWCJ2BGH,95W,SocketAM2+ 2.00G 0301GO
Athlon X2 BE-2400 (DO),1M,45W,rev.G2,SocketAM2 2.00G 0301GO
Phenom IIX2 545 (HDX545WFK2DGI),3.0GHz,80W,rev.C2,SocketAM3,Dual-Core 2.00G 0301GO
Phenom IIX2 545( HDX545WFK2DGM),3.0GHz,512KB,rev.C3,80W,SocketAM3 2.00G 0301GO
Phenom IIX2 550 (HDZ550WFK2DGI),3.1GHz,80W,rev.C2,SocketAM3,Dual-Core 2.00G 0301GO
Phenom IIX2 550( HDX550WFK2DGM),3.1GHz,512KB,rev.C3,80W,SocketAM3 2.00G 0301GO
Phenom IIX2 560(HDZ560WFK2DGM),3.3GHz,512KB,rev.C3,80W,SocketAM3 ALL 2501GO
Phenom IIX3 700e (HD700EOCK3DGI),2.4GHz,65W,rev.C2,SocketAM3,Triple-Core 2.00G 0301GO
Phenom IIX3 705e (HD705EOCK3DGI),2.5GHz,65W,rev.C2,SocketAM3,Triple-Core 2.00G 0301GO
Phenom IIX3 710 (HDX710WFK3DGI),2.6GHz,95W,rev.C2,SocketAM3,Triple-Core 2.00G 0301GO
Phenom IIX3 715 (HDZ715WCJ3DGI),2.8GHz,95W,rev.C2,SocketAM2+,Triple-Core 2.00G 0301GO
Phenom IIX3 720 (HDX720WFK3DGI),2.8GHz,95W,rev.C2,SocketAM3,Triple-Core 2.00G 0301GO
Phenom IIX3 720 (HDZ720WFK3DGI),2.8GHz,95W,rev.C2,SocketAM3,Triple-Core 2.00G 0301GO
Phenom IIX3 740 (HDZ740WFK3DGI),3.0GHz,95W,rev.C2,SocketAM3,Triple-Core 2.00G 0301GO
Phenom IIX4 805 (HDX805WFK4FGI),2.5GHz,95W,rev.C2,SocketAM3,Quad-Core 2.00G 0301GO
Phenom IIX4 810 (HDX810WFK4FGI),2.6GHz,95W,rev.C2,SocketAM3,Quad-Core 2.00G 0301GO
Phenom IIX4 820 (HDX820WFK4FGI),2.8GHz,95W,rev.C2,SocketAM3,Quad-Core 2.00G 0301GO
Phenom IIX4 900e (HD900EOCK4DGI),2.4GHz,65W,rev.C2,SocketAM3,Quad-Core 2.00G 0301GO
Phenom IIX4 905e (HD905EOCK4DGI),2.5GHz,65W,rev.C2,SocketAM3,Quad-Core 2.00G 0301GO
Phenom IIX4 910 (HDX910WFK4DGI),2.6GHz,95W,rev.C2,SocketAM3,Quad-Core 2.00G 0301GO
Phenom IIX4 910E(HD910EOCK4DGM),2.6GHz,65W,rev.C3,SocketAM3,Quad-Core GO
Phenom IIX4 920 (HDX920XCJ4DGI),2.8GHz,125W,rev.C2,SocketAM2+,Quad-Core 2.00G 0301GO
Phenom IIX4 925 (HDX925WFK4DGI),2.8GHz,95W,rev.C2,SocketAM3,Quad-Core 2.00G 0301GO
Phenom IIX4 925 (HDX925WFK4DGM),2.8GHz,95W,rev.C3,SocketAM3,Quad-Core 2.00G 0301GO
Phenom IIX4 940 (HDZ940XCJ4DGI),3.0GHz,125W,rev.C2,SocketAM2+,Quad-Core 2.00G 0301GO
Phenom IIX4 945 (HDX945FBK4DGI),3.0GHz,125W,rev.C2,SocketAM3,Quad-Core 2.00G 0301GO
Phenom IIX4 945 (HDX945WFK4DGI),3.0GHz,2048KB,95W,rev.C2,SocketAM3,Quad-Core 2.00G 0301GO
Phenom IIX4 945 (HDX945WFK4DGM),3.0GHz,2048KB,95W,rev.C3,SocketAM3,Quad-Core 2.00G 0301GO
Phenom IIX4 955 (HDX955FBK4DGI),3.2GHz,125W,rev.C2,SocketAM3,Quad-Core 2.00G 0301GO
Phenom IIX4 955 (HDX955FBK4DGM),3.2GHz,125W,rev.C3,SocketAM3,Quad-Core 2.00G 0301GO
Phenom IIX4 955 (HDX955WFK4DGM),3.2GHz,95W,rev.C3,SocketAM3,Quad-Core ALL 0601GO
Phenom IIX4 955 (HDZ955FBK4DGI),3.2GHz,125W,rev.C2,SocketAM3,Quad-Core 2.00G 0301GO
Phenom IIX4 955 (HDZ955FBK4DGM),3.2GHz,125W,rev.C3,SocketAM3,Quad-Core ALL 0302GO
Phenom IIX4 960T (HD96ZTWFK4DGR),3.0GHz,95W,rev.E0,SocketAM3,Quad-Core ALL 2005GO
Phenom IIX4 965 (HDZ965FBK4DGM),3.4GHz,125W,rev.C3,SocketAM3,Quad-Core 2.00G 0301GO
Phenom IIX6 1035T(HDT35TWFK6DGR),2.6GHz,95W,rev.E0,SocketAM3,6-Core ALL 2002GO
Phenom IIX6 1045T(HDT45TWFK6DGR),2.7GHz,95W,rev.E0,SocketAM3,6-Core ALL 2501GO
Phenom IIX6 1055T(HDT55TFBK6DGR),2.8GHz,125W,rev.E0,SocketAM3,6-Core ALL 2004GO
Phenom IIX6 1055T(HDT55TWFK6DGR),2.8GHz,125W,rev.E0,SocketAM3,6-Core ALL 2004GO
Phenom IIX6 1075T(HDT75TFBK6DGR),3.0GHz,125W,rev.E0,SocketAM3,6-Core ALL 2501GO
Phenom IIX6 1090T(HDT90ZFBK6DGR),3.2GHz,125W,rev.E0,SocketAM3,6-Core ALL 2004GO
Phenom X3 8250e (HD8250ODJ3BGH),1.9GHz,rev.B3,65W,SocketAM2+,Triple-Core 2.00G 0301GO
Phenom X3 8450e (HD8450ODJ3BGH),2.1GHz,rev.B3,65W,SocketAM2+,Triple-Core 2.00G 0301GO
Phenom X3 8600(HD8600WCJ3BGD),2.3GHz,95W,rev.B2,SocketAM2+,Triple-Core 2.00G 0301GO
Phenom X3 8650 (HD8650WCJ3BGH),2.3GHz,95W,rev.B3,SocketAM2+,Triple-Core 2.00G 0301GO
Phenom X3 8750 (HD875ZWCJ3BGH),2.4GHz,rev.B3,95W,SocketAM2+,Triple-Core 2.00G 0301GO
Phenom X3 8850 (HD8850WCJ3BGH),2.4GHz,rev.B3,95W,SocketAM2+,Triple-Core 2.00G 0301GO
Phenom X4 9150 (HD9150ODJ4BGH),1.8GHz,65W,rev.B3,SocketAM2+,Quad-Core 2.00G 0301GO
Phenom X4 9350 (HD9350ODJ4BGH),2.0GHz,65W,rev.B3,SocketAM2+,Quad-Core 2.00G 0301GO
Phenom X4 9450e (HD9450ODJ4BGH),2.1GHz,65W,rev.B3,SocketAM2+,Quad-Core 2.00G 0301GO
Phenom X4 9500 (HD9500WCJ4BGD),2.2GHz,rev.B2,95W,SocketAM2+,Quad-Core 2.00G 0301GO
Phenom X4 9550 (HD9550WCJ4BGH),2.2GHz,rev.B3,95W,SocketAM2+,Quad-Core 2.00G 0301GO
Phenom X4 9600 (HD9600WCJ4BGD),2.3GHz,95W,rev.B2,SocketAM2+,Quad-Core 2.00G 0301GO
Phenom X4 9650 (HD9650WCJ4BGH),2.3GHz,95W,rev.B3,SocketAM2+,Quad-Core 2.00G 0301GO
Phenom X4 9750 (HD9750WCJ4BGH),2.4GHz,95W,rev.B3,SocketAM2+,Quad-Core 2.00G 0301GO
Phenom X4 9750 (HD9750XAJ4BGH),2.4GHz,125W,rev.B3,SocketAM2+,Quad-Core 2.00G 0301GO
Phenom X4 9850 (HD9850WCJ4BGH,rev.B3,SocketAM2+,Quad-Core 2.00G 0301GO
Phenom X4 9850 (HD985ZXAJ4BGH),2.5GHz,125W,rev.B3,SocketAM2+,Quad-Core 2.00G 0301GO
Phenom X4 9950 (HD995ZXAJ4BGH),2.6GHz,125W,rev.B3,SocketAM2+,Quad-Core 2.00G 0301GO
Sempron 140,SDX140HBK13GQ,2.7GHz,1024K,rev.C2,45W,SocketAM3 2.00G 0301GO
Sempron 145,SDX145HBK13GM,2.8GHz,1024K,rev.C3,45W,SocketAM3 ALL 2005GO
Sempron LE-1250 (DP),512K,rev.G2,45W,SocketAM2 2.00G 0301GO
Sempron X2 180,SDX180HDK22GM,2.4GHz,512Kx2,rev.C3,45W,SocketAM3 ALL 2002GO