ASROCK 939N68PV-GLAN User Manual page 25

Though this motherboard provides 4-Pin CPU fan (Quiet Fan) support, the 3-Pin
CPU fan still can work successfully even without the fan speed control function.
If you plan to connect the 3-Pin CPU fan to the CPU fan connector on this
motherboard, please connect it to Pin 1-3.
ATX Power Connector
(24-pin ATXPWR1)
(see p.10, No. 3)
Though this motherboard provides 24-pin ATX power connector,
it can still work if you adopt a traditional 20-pin ATX power supply.
To use the 20-pin ATX power supply, please plug your power
supply along with Pin 1 and Pin 13.
ATX 12V Power Connector
(4-pin ATX12V1)
(see p.10 No. 1)
Serial port Header
(9-pin COM1)
(see p.10 No.24)
Pin 1-3 Connected
3-Pin Fan Installation
Please connect an ATX power
12 24
supply to this connector.
1 13
20-Pin ATX Power Supply Installation
Please note that it is necessary
to connect a power supply with
ATX 12V plug to this connector.
Failing to do so will cause power
up failure.
This COM1 header supports a
RRXD1
DDTR#1
serial module.
DDSR#1
CCTS#1
1
RRI#1
RRTS#1
GND
TTXD1
DDCD#1
2 5 2 5 2 5 2 5 2 5
12 24
1 13