You cna find information like that at the motherboard manufacturers website. In Asus's case, choose Support, choose troubleshooting, choose CPU support. Use the drop down menus to show your mobo. MDE is incorrect in this case.
Athlon 64 2800+ (Socket754) ALL
0112
Athlon 64 3000+ (Socket754, revE6) ALL
0203
Athlon 64 3000+ (Socket754) ALL
0203
Athlon 64 3200+ (Socket754) ALL
0112
Athlon 64 3200+ (Socket754, revE6) ALL
0207
Athlon 64 3400+ (Socket754) ALL
0112
Athlon 64 3700+ (Socket754) ALL
0112
Sempron 2500+ 64bit(rev.E6) (Socket754) ALL
0201
Sempron 2600+ (rev.D) (no CnQ) (Socket754) ALL
0112
Sempron 2600+ 64bit(rev.E3) (no CnQ) (Socket754) ALL
0201
Sempron 2600+ 64bit(rev.E6) (Socket754) ALL
0201
Sempron 2800+ (rev.D) (no CnQ) (Socket754) ALL
0112
Sempron 2800+ 64bit(rev.E3) (no CnQ) (Socket754) ALL
0201
Sempron 2800+ 64bit(rev.E6) (Socket754) ALL
0201
Sempron 3000+ (rev.D) (Socket754) ALL
0112
Sempron 3000+ 64bit(rev.E3) (Socket754) ALL
0201
Sempron 3000+ 64bit(rev.E6) (Socket754) ALL
0201
Sempron 3100+ (CG version) (Socket754) ALL
0112
Sempron 3100+ (rev.D) (Socket754) ALL
0112
Sempron 3100+ 64bit(rev.E3) (Socket754) ALL
0201
Sempron 3100+ 64bit(rev.E6) (Socket754) ALL
0201
Sempron 3300+ (rev.D) (Socket754) ALL
0112
Sempron 3300+ 64bit(rev.E3) (Socket754) ALL
0201
Sempron 3300+ 64bit(rev.E6) (Socket754) ALL
0201
Sempron 3400+ 64bit(rev.E6) (Socket754) ALL
0201
the ALL represents the PCB revision, 4 digits are BIOS rev's.
and no, 754 doesn't support dual core.