@Ehryk:
AHA!!!
Yep, ran into that too, it was the next thing I would have recommended to check against, however, this applies only to internal headers, external D-SUB connectors are everywhere the same. If you say you had partial success with USB, then after the ACPI trick you should have noticed success on the rear D-SUB too. And only after that, try the internal header… 8)
This is not SuperMicro-specific, this dates from the 1990's, there were always two flavours of interal header pinout: IBM/DTK WIRING SCHEME and EVEREX/ASUS WIRING SCHEME.
It's only a question of which manufacturer adopts which standard, nothing more.
SERIAL MOTHERBOARD CABLE 10 PIN DIL TO DB-9
(IBM/DTK WIRING SCHEME)
This is the ribbon cable from the MB serial
connector to the DB-9/DB-25 COM connector
DIL DB-9 DB-25
1 -------------- 1 DCD __________ 8
6 -------------- 2 RX ___________ 3
2 -------------- 3 TX ___________ 2
7 -------------- 4 DTR __________ 20
3 -------------- 5 GND __________ 7
8 -------------- 6 DSR __________ 6
4 -------------- 7 RTS __________ 4
9 -------------- 8 CTS __________ 5
5 -------------- 9 RI ___________ 22
10 ------------- 10 N/C OR KEY
SERIAL MOTHERBOARD CABLE 10 PIN DIL TO DB-9
(EVEREX/ASUS WIRING SCHEME)
This is the ribbon cable from the MB serial
connector to the DB-9/DB-25 COM connector
DIL DB-9 DB-25
1 -------------- 1 DCD __________ 8
2 -------------- 2 RX __________ 3
3 -------------- 3 TX __________ 2
4 -------------- 4 DTR __________ 20
5 -------------- 5 GND __________ 7
6 -------------- 6 DSR __________ 6
7 -------------- 7 RTS __________ 4
8 -------------- 8 CTS __________ 5
9 -------------- 9 RI __________ 22
10 ------------- 10 N/C OR KEY