It means that data of the memory registry of K8 processor has been updated to DMI when the system is turned on. Those data are aimed to be written back to processor when PC wakes up from sleep mode of S3STR.
The 20-pin connector belongs to older ATX standard while 24-pin connector follows newer ATX standard. The 24-pin connector just the 20-pin cable with 4 extra wires to provide extra current. As long as your power supply can provide sufficient power to the motherboard, you can still use 20-pin power supply.