Please check M845AD PCB version as following:PCB: V1.2 did support S1/S3 full functions.PCB: V2.0X didn't support S3, support S1.

No, the MB845AD V2.0 comes with Intel ICH2 chip which supports USB 1.1 only.

No, the MB845AD V2.0 supports AGP mode up to 4X (1.5V only). You can install an AGP 8X card on this MB but the card will run with AGP 4X mode.

No, the MB845AD v2.0 only supports to DDR266 maximum.

No, the MB845AD V2.0 supports DDR RAM up to 266MHz.

MB845AD v2.X ,maximum CPU and HDD supported information as below, HDD:250G Pentium 4 400Mhz FSB (256K/512K L2 cache) CPU – 2.2G. Pentium 4 533Mhz FSB (512K L2 cache) CPU –No support Pentium 4 800Mhz FSB (512K L2 cache) CPU –No support Celeron 400Mhz FSB (128K L2 cache) CPU – 1.8G Mhz Pentium 4 533FSB (1M L2 cache) NW CPU – 2.8G Mhz Celeron D 400Mhz FSB (256K L2 cache) CPU – No support