J&W AMD 790GX User manual

AMD 790GX
Socket AM2/AM2+/AM3 Processor Mainboard
User’s Manual
Rev: 1.0, Apr 2009
P/N: 82E790GX10
Motherboard

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The intellectual property of this manual belongs to our company. The ownership of all of the
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We compiled this manual based on our careful attitude, but we can not guarantee the accuracy
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meanings, and we won't commit users' misunderstanding of the typesetting error.
Our products are in continuous improvement and updating, Therefore, we retain the right that
we won't give notice to the users in future.
Copyright
All of the trademarks in this manual belong to their own registered companies.
All of the products name is only for identication, its title belongs to its manufacturer or brand
owner.

Table of Contents
Chapter 1 Introduction ........................................................................................... 3
1.1 Package Checklist ...............................................................................................................
3
1.2 Specications ...................................................................................................................... 4
1.3 Mainboard Layout ...............................................................................................................
5
1.4 Connecting Rear Panel I/O Devices ............................................................................. 6
Chapter 2 Hardware Setup ...................................................................................... 7
2.1 Choosing a Computer Chassis .............................................................................................. 7
2.2 Installing Mainboard ............................................................................................................ 7
2.3 Installation of the CPU and CPU Cooler.................................................................................. 8
2.3.1 Installation of the CPU ............................................................................................................. 8
2.3.2 Installation of the CPU Cooler ................................................................................................... 9
2.4 Installation of Memory Modules ............................................................................................ 9
2.5 Connecting Peripheral Devices............................................................................................. 10
2.5.1 Floppy and IDE Disk Drive Connectors ...................................................................................... 10
2.5.2 Serial ATA Connectors ............................................................................................................. 10
2.5.3 PCI and PCI Express slots ........................................................................................................ 10
Chapter 3 Jumpers & Headers Setup .................................................................... 11
3.1 Checking Jumper Settings ..................................................................................................
11
3.2 CMOS Memory Clearing Header .......................................................................................... 11
3.3 Keyboard Power Function(JKB) ........................................................................................... 11
3.4
Dual BIOS Function (DDR2 & DDR3 BIOS)
........................................................................... 12
3.5 Serial Port Header(JCOM1) ................................................................................................. 1 2
3.6 JHPD Jumper & JDVI_HDMI Jumper .................................................................................... 13
3.7 JHDT Jumper ..................................................................................................................... 13
3.8 JP1/JP2/JP3/JP4 Jumper ..................................................................................................... 14
3.9
D32, D33 LEDs introduction
................................................................................................ 14
3.10 FAN Power Connectors ..................................................................................................... 15
3.11 Front Panel Switches & Indicators Headers ......................................................................... . 15
3.12 Additional USB Port Headers ............................................................................................. . 16
3.13 Front Panel Audio & Internal Audio Connectors .................................................................... . 16
3.14 S/PDIF out connection Header........................................................................................... . 17
3.15 ATX Power Input Connectors ............................................................................................ . 17
Chapter 4 BIOS Setup Utility ................................................................................. 18
4.1 About BIOS Setup ............................................................................................................. 18
4.2 To Run BIOS Setup ........................................................................................................... 18
4.3 About CMOS...................................................................................................................... 18
4.4 The POST (Power On Self Test)........................................................................................... 18
4.5 BIOS Setup — CMOS Setup Utility..................................................................................... .. 19
4.5.1 CMOS Setup Utility ............................................................................................................. . .. 19
4.5.2 Control Keys ........................................................................................................................ 19
4.5.3 Main Setting ........................................................................................................................ 20
4.5.4 Advanced Setting ................................................................................................................. 23
4.5.5 Boot Setting.......................................................................................................................... 27
4.5.6 Security Setting..................................................................................................................... 28
4.5.7 Power Setting........................................................................................................................ . 28
4.5.8 JUSTw00t! Settings............................................................................................................... ... 32
4.5.9 Exit Options........................................................................................................................... . 35
Chapter 5 Driver Installation ................................................................................ 38
APPENDIX 1 (AMIBIOS easy code list only for your reference)...........................
40

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AMD 790GX User's Manual
Chapter 1 Introduction
1.1 Package Checklist
Thank you for choosing our product.
Please check the following packing and accessories, if there is any broken or part missing,
please contact with your franchiser.
• HDD Cable X 1
• Rear I/O Panel X 1
• User Manual X 1
• Driver/Utility CD X 1
• SATA Power Cable X 1
• SATA Single Cable X 2
• FDD Cable X 1 (Optional)
The items listed above are for reference only, and are subject to change without notice.

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AMD 790GX User's Manual
1.2 Specications
CPU
-Supports AMD®Socket AM2+/ AM2 / AM3 processors
-AMD®Phenom™ II / Phenom™ / Athlon™ 64 FX / Athlon™ 64 X2 Dual Core/
Athlon™ 64 / Sempron™ processors
-Hyper Transport Bus 5200/2000 MT/s (HT 3.0/1.0)
Chipset
- AMD®790GX + SB750
- Built in Radeon™ HD 3300 Graphics, DirectX®10 Ready
- Onboard 128MB DDR3 sideport memory (Optional)
Memory
- Supports 2 x 1.8V DDR2 DIMM sockets supporting up to 8 GB of system memory
- Supports 2 x 1.5V DDR3 DIMM sockets supporting up to 8 GB of system memory
- Supports Dual channel memory architecture
- Supports for DDR2 1066/800/667 MHz memory modules
Note: 1066 MHz memory support is dependent on the CPU being used.
- Supports for DDR3 1333/1066/800 MHz memory modules
BIOS
- AMI BIOS,supports Plug&Play
- Supports BIOS ROM Write Protect
- Supports Advanced Power Management ACPI,STR
- 1 x DDR2 BIOS & 1 x DDR3 BIOS (Dual BIOS)
- CPU temperature, Fan speed, System Voltage monitoring
Rear Panel I/O
- 1 x PS/2 Mouse port
- 1 x PS/2 Keyboard port
- 4 x USB 2.0 ports, USB 1.1 is compliant
- 1 x HDMI port
- 1 x DVI port
- 1 x VGA port
- 1 x Coaxial S/PDIF IN port
- 1 x Optical S/PDIF Out port
- 1 x eSATA port
- 1 x RJ45 port
- 6 x Audio jacks (Line In / Line Out / MIC In/ Rear Speaker Out /
Center / Subwoofer Speaker Out / Side Speaker Out)
Internal I/O
Connectors
- 1 x 24-pin ATX main power connector
- 1 x 8-pin ATX 12V power connector
- 1 x Floppy disk drive connector
- 1 x IDE connector
- 6 x SATA 3Gb/s connectors, supports SATA RAID 0, RAID 1, RAID 0+1, RAID 5
and RAID 10
- 1 x CPU fan header
- 2 x System fan headers
- 1 x CD audio in header
- 1 x Front panel header
- 1 x Front panel audio header
- 1 x S/PDIF In header
- 1 x S/PDIF Out header
- 1 x IR header
- 1 x Speaker header
- 1 x EZ power switch (Optional)
- 1 x EZ reset switch (Optional)
- 1 x Serial port header
- 1 x Debug LED (Optional, please reference appendix 1)
- 1 x IEEE 1394a header
- 3 x USB 2.0 headers for additional 6 USB 2.0 ports (by cables)
- 1 x eSATA connector
Sound - Onboard 6-channel/8-channel HD Audio Codec (Optional)
- Front Panel Jumper, provides stereo MIC port on front panel
Onboard LAN - Onboard 10/100/1000Mbps compatible LAN (Optional)
Expansion Slots
- 1 x PCI Express x16 slot (PCI Express 2.0)
- 1 x PCI Express x8 slot
- 1 x PCI Express x4 slot
- 1 x PCI Express x1 slot
- 2 x PCI slots, support PCI Bus interface v2.3 compliant
Form Factor - ATX (243.8mm*304.8mm)

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AMD 790GX User's Manual
1.3 Mainboard Layout
(This picture is only for reference)

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AMD 790GX User's Manual
1.4 Connecting Rear Panel I/O Devices
The rear I/O of this motherboard provides the following I/O ports:
(This picture is only for reference)
• PS/2 Mouse: Connects to PS/2 mouse.
• PS/2 Keyboard: Connects to PS/2 keyboard.
• DVI: Connects to monitor input.
• VGA: Connects to monitor input.
• HDMI:Connects to multimedia devices of HDMI protocol.
• SPDIF IN:This connector provides an S/PDIF-IN connection.
• SPDIF OUT: Connects to analog/digital audio device.
• eSATA:Connects to peripherial SATA devices.
• 1394: The IEEE 1394a port provides high-speed connectivity for video devices, music
equipment, storage peripherals or other portable devices.
• USB: Connects to USB devices such as scanner, digital speakers, monitor, mouse, keyboard,
hub, digital camera, joystick etc.
• LAN: Connects to Local Area Network.
• AUDIO1:
Cen./Sub. (Center / Subwoofer): Connects to the center and subwoofer channel in the 7.1
channel audio system.
R.L./R.R. (Rear Left / Rear Right): Connects to the rear left and rear right channel in the 7.1
channel audio system.
S.L./S.R. (Surround Left / Surround Right): Connects to the surround left and surround right
channel in the 7.1 channel audio system.
Line-In: Connects to the line out from external audio sources.
Line-Out: Connects to the front left and front right channel in the 7.1-channel or regular
2-channel audio system.
Mic-In: Connects to the plug from external microphone.

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AMD 790GX User's Manual
Chapter 2 Hardware Setup
2.1 Choosing a Computer Chassis
• Choose a chassis big enough to install this mainboard.
• As some features for this mainboard are implemented by cabling connectors on the
mainboard to indicators and switches or buttons on the chassis, make sure your chassis
supports all the features required.
• If there is possibility of adopting some more hard drives, make sure your chassis has
sufcient power and space for them.
• Most chassis have alternatives for I/O shield located at the rear panel. Make sure the I/O
shield of the chassis matches the I/O port conguration of this mainboard. You can nd
an I/O shield specically designed for this mainboard in its package.
2.2 Installing Mainboard
Most computer chassis have a base with many mounting holes to allow the mainboard to
be securely attached, and at the same time, prevent the system from short circuits. There
are two ways to attach the mainboard to the
chassis base: (1) with studs, or (2) with spacers.
Basically, the best way to attach the board is with
studs. Only if you are unable to do this should you
attach the board with spacers. Line up the holes on
the board with the mounting holes on the chassis.
If the holes line up and there are screw holes, you
can attach the board with studs. If the holes line
up and there are only slots, you can only attach with
spacers. Take the tip of the spacers and insert them
into the slots. After doing this to all the slots, you can slide the board into position aligned
with slots. After the board has been positioned, check to make sure everything is OK before
putting the chassis back on.
To install this mainboard:
1. Locate all the screw holes on the mainboard and the chassis base.
2. Place all the studs or spacers needed on the chassis base and have them tightened.
3. Face the mainboard’s I/O ports toward the chassis’s rear panel.
4. Line up all the mainboard’s screw holes with those studs or spacers on the chassis.
5. Install the mainboard with screws and have them tightened.
The mainboard and its component layouts illustrated in this chapter were
based mainly on model “AMD 790GX”, unless specically stated.
Always power off the computer and unplug the AC power cord before adding or removing
any peripheral or component. Failing to do so may cause severe damage to your
mainboard and/or peripherals. Plug in the AC power cord only after you have carefully
checked everything.
To prevent shorting the PCB circuit, please REMOVE the metal studs or spacers if they are
already fastened on the chassis base and are without mounting-holes on the mainboard to
align with.

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AMD 790GX User's Manual
2.3 Installation of the CPU and CPU Cooler
Before installing the CPU, please comply with the following conditions:
1. Please make sure that the mainboard supports the CPU.
2. Please take note of the one indented corner of the CPU. If you install the CPU in the wrong
direction, the CPU will not insert properly. If this occurs, please change the insert direction
of the CPU.
3. Please add an even layer of heat sink paste between the CPU and CPU cooler.
4. Please make sure the CPU cooler is installed on the CPU prior to system use, otherwise
overheating and permanent damage of the CPU may occur.
5. Please set the CPU host frequency in accordance with the processor specications. It is not
recommended that the system bus frequency be set beyond hardware specications since
it does not meet the required standards for the peripherals. If you wish to set the frequen-
cy beyond the proper specications, please do so according to your hardware
specications including the CPU, graphics card, memory, hard drive, etc.
2.3.1 Installation of the CPU
1. Unlock the socket by pressing the
lever sideways, then lift it up to a 90
o
.
2. Position the CPU above the socket such
that the CPU corner with the gold
triangle matches the socket corner with
a small triangle.
3. Carefully insert the CPU into the socket
until it ts place.
4. When the CPU is in place, push down
the socket lever to secure the CPU.
The lever clicks on the side tab to
indicate that it is locked.
Figure 1
Figure 2
Figure 3

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AMD 790GX User's Manual
2.3.2 Installation of the CPU Cooler
For proper installation, please kindly refer to the instruction manuals of your CPU Cooler.
2.4 Installation of Memory Modules
This mainboard provides two 240-pin DDRII (Double Data Rate) DIMM slots and two 240-pin
DDR3 DIMM slots, and supports Dual Channel Memory Technology. For dual channel congu-
ation, you always need to install two identical (the same brand, speed, size and chip-type)
memory modules in the DIMM slots to activate Dual Channel Memory Technology. Otherwise,
it will operate at single channel mode.
DIMM1 and DIMM2 slot are DDR2 DIMM slots, DIMM3 and DIMM4 are DDR3 DIMM slots.
Note: DDR2 DIMMs and DDR3 DIMMS CANNOT be used simultaneously!
Please refer to following of gure to match your cpu and DIMM.
Support Model:
1 AM2 CPU DDR2 Memory
2 AM2+ CPU DDR2 Memory
3 AM3 CPU DDR2 Memory
4 AM3 CPU DDR3 Memory
Note: LEDs D32 and/or D33 will light up to warn you for incorrect congurations if you don't
follow the correct CPU and memory combination. Further introduction of D32 and D33
LEDs is on page 14 for your referenece.
DIMM installation: Please insert the DIMMs into the DIMM slots vertically downwards.
Make sure you check the notch key position to be matched with the
DIMMs before you plugging them into the slots.
Note: DDR2 and DDR3 DIMMs have different notch key positions.
To install system memory:
1. Power off the computer and unplug the
AC power cord before installing or
removing memory modules.
2. Locate the DIMM slot on the board.
3. Hold two edges of the DIMM module
carefully, keep away from touching its
connectors.
4. Align the notch key on the module with
the rib on the slot.
5. Firmly press the module into the slots until the ejector tabs at both sides of the slot
automatically snap into the mounting notch. Do not force the DIMM module in with extra
force as the DIMM module only ts in one direction.
6. To remove the DIMM modules, push the two ejector tabs on the slot outward
simultaneously, and then pull out the DIMM module.
Static electricity can damage the electronic components of the computer or optional
boards. Before starting these procedures, ensure that you are discharged of static
electricity by touching a grounded metal object briey.

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AMD 790GX User's Manual
2.5 Connecting Peripheral Devices
2.5.1 Floppy and IDE Disk Drive Connectors
The FDD connector connects up to two oppy drives with a 34-wire, 2-connector oppy
cable.Connect the single end at the longer length of ribbon cable to the FDD on the board,
the two connectors on the other end to the oppy disk drives connector. Generally you need
only one oppy disk drive in your system.
2.5.2 Serial ATA Connectors
Each SATA connector serves as one single channel to connect one SATA device by SATA
cable.
2.5.3 PCI and PCI Express slots
Install PCI Express X16 graphics card into slot “PCIE1”.
Install PCI Express X1 card into slot “PCIE2”.
Install PCI Express X8 card into slot “PCIE3”.
Install PCI Express X4 card into slot “PCIE4”.
Install PCI card into slots “PCI1” or “PCI2” .
Each of the IDE port connects up to two IDE
drives at Ultra ATA 133/100/66/33 mode by
one 40-pin, 80-conductor,and 3-connector Ultra
ATA/66 ribbon cables.
Connect the single end (blue connector) at the
longer length of ribbon cable to the IDE port of
this board, the other two ends (gray and black
connector) at the shorter length of the ribbon
cable to the connectors of your hard drives.
Make sure to congure the “Master” and “Slave” relation
before connecting two drives by one single ribbon cable.
The red line on the ribbon cable must be aligned with
pin-1 on both the IDE port and the hard-drive connector.
The red line on the ribbon cable must be aligned with pin-1 on both the FDD port and the oppy connector.
• eSATA: Connect to peripherial SATA devices.The
peripherial SATA devices must connect inside
SATA connectors. (Optional)

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AMD 790GX User's Manual
Chapter 3 Jumpers & Headers Setup
3.1 Checking Jumper Settings
• For a 2-pin jumper, plug the jumper cap on both
pins will make it CLOSE (SHORT). Remove the
jumper cap, or plug it on either pin (reserved for
future use) will leave it at OPEN position.
• For 3-pin jumper, pin 1~2 or pin 2~3 can be
shorted by plugging the jumper cap in.
How to identify the PIN1 jumpers?
Please check the mainboard carefully, the PIN1
is marked by "1" or white thick line.
3.2 CMOS Memory Clearing Header
The time to clear the CMOS memory occurs when (a)
the CMOS data becomes corrupted, (b) you forgot
the supervisor or user password preset in the BIOS
menu, (c) you are unable to boot-up the system
because the CPU ratio/clock was incorrectly set in the
BIOS menu, or (d) whenever there is modication on
the CPU or memory modules.
This header uses a jumper cap to clear the CMOS
memory and have it recongured to the default
values stored in BIOS.
• Pins 1 and 2 shorted
(Default): Normal
operation.
• Pins 2 and 3 shorted:
Clear CMOS memory.
To clear the CMOS memory and load in the default values:
1. Power off the system.
2. Set pin 2 and pin 3 shorted by the jumper cap. Wait for a few seconds. Set the jumper
cap back to its default settings --- pin 1 and pin 2 shorted.
3. Power on the system.
4. For incorrect CPU ratio/clock settings in the BIOS, press <Del> key to enter the BIOS
setup menu right after powering on system.
5. Set the CPU operating speed back to its default or an appropriate value.
6. Save and exit the BIOS setup menu.
3.3 Keyboard Power Function(JKB)
Pin 1-2 short: Disabled power on by keyboard
Pin 2-3 short: Support power on by keyboard

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AMD 790GX User's Manual
3.4 Dual BIOS Function (DDR2 & DDR3 BIOS)
JBIOSSLC
NC AUTO Automatically detects the memory type and
select the corresponding BIOS.
1-2 DDR2_Bios Force using the DDR2 BIOS.
2-3 DDR3_Bios Force using the DDR3 BIOS.
3.5 Serial Port Header (Optional)
Pin Pin Assignment Pin Pin Assignment
1 DCD 2 RXD
3 TXD 4 DTR
5 GND 6 DSR
7 CTS 8 RTS
9 RI
This JCOM1 header supports a serial port module.

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AMD 790GX User's Manual
3.6 JHPD Jumper & JDVI_HDMI Jumper
Pin No. Denition
1-2 DVI
2-3 HDMI
JDVI_HDMI Jumper
This motherboard is built with the onboard DVI and HDMI
connectors, by default the primary output is through the
DVI port (pin#1-2), if you are going to connect the video
output to a HDMI device, please short this set of jumper to
pin #2-3.
Pin No. Denition
1-2 Auto
2-3 DVI/HDMI EN
JHPD Jumper
While JHPD jumper is being shorted at pin#1-2, it will
automatically detect the HDMI or DVI device connected,
however, when certain DVI or HDMI devices can't be
detected, please short the jumper to pin #2-3 to manually
override the setting.
3.7 JHDT Jumper (for AMD OverDrive)
1-2（Default）Normal HDT Default status.
2-3 OVER_DRIVE Ena ble to a llow t he AM D
OverDrive feature to function.
JHDT Jumper

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AMD 790GX User's Manual
3.9 D32, D33 LEDs introduction
3.8 JP1/JP2/JP3/JP4 Jumper
1-2（Default）Normal PCIE1 slot: x16 / PCIE3 slot: Disabled
2-3 CrossFire PCIE1 slot: x8/ PCIE3 slot: Enabled,
x8
There are 2 LEDs (D32 & D33), located as shown on the picture,
following is the introduction of the status of these 2 LEDs when
INCORRECT CPU & memory combinations are being installed.
LED Status introduction
D32
When DDR2 and DDR3 memories are installed at
the same time, this LED will light up to warn you,
DDR2 and DDR3 memories CANNOT be installed
simultaneously.
D33
When AM2/AM2+ CPU is being installed with DDR3
memory, this LED will light up to warn you, AM2/
AM2+ CPU doesn't support DDR3 memory.
CrossFire Jumper

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AMD 790GX User's Manual
3.10 FAN Power Connectors
These connectors each provide power to the cooling fans installed in your system.
CFAN or CFAN1: CPU Fan Power Connector
SFAN1/2: System Fan Power Connector
3.11 Front Panel Switches & Indicators Headers
SPEAKER
HDD_LED (Hard Driver LED Header)
Connect the HDD LED cable to these PINs, in order to see the HDD status
RESET (On the board lower right-hand corner, the "RESET" is the reset switch also)
This connector connects to the case-mounted reset switch for rebooting your computer
without having to turn off your power switch. This is a preferred method of rebooting in
order to prolong the lift of the system’s power supply.
PWR-ON (
On the board lower right-hand corner, the "POWER_ON" is the power on button also
)
This connector connects to the case-mounted power switch to power ON/OFF the system.
SPEAKER (Speaker)
This 4-pin connector connects to the case-mounted speaker. You should follow the
instruction of the speaker cable.
These fan connectors are not jumpers. DO NOT place
jumper caps on these connectors.

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AMD 790GX User's Manual
Pin Pin Assignment Pin Pin Assignment
1 VCC 2 VCC
3 Data 0- 4 Data 0-
5 Data 0+ 6 Data 0+
7 Ground 8 Ground
9 No Pin 10 NC
3.12 Additional USB Port Headers
3.13 Front Panel Audio & Internal Audio Connectors
CD_IN:
Pin No. Denition
1 CD-L
2 GND
3 GND
4 CD-R
Pin No. Header HD Audio Denition AC97 Audio Denition
1 PORT1L Microphone Microphone
2 AGND Ground Ground
3 PORT1R Microphone N/A
4 PRESENCE# Detection sense line from front HD audio. N/A
5 PORT2R Right Channel Right Channel
6 SENSE1_RETURN To detect Microphone sense. N/A
7 SENSE_SEND Send Jack detection sense from the high denition audio codec. N/A
8 No Pin N/A N/A
9 PORT2L Left Channel Left Channel
10 SENSE2_RETURN To detect Right and Left channel N/A

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AMD 790GX User's Manual
3.14 S/PDIF Output Connection Header (Optional)
S/PDIF (Sony/Philips Digital Interface) is a standard audio transfer le format. It is usually
found on digital audio equipment such as a DAT (Digital Audio Tape) machine or audio
processing device. It allows the transfer of audio from one le to another without the
conversion to and from an analog format, which could degrade the signal quality.
3.15 ATX Power Input Connectors
This mainboard provides two power connectors to connect power supplier.
This connector allows you to connect an ATX 24-pin power supply.To connect the ATX 24-pin
power supply,make sure the plug of the power supply is inserted in the proper orientation
and the pins are aligned. Then push down the power supply rmly into the connector.
Your may use the 20-pin ATX power supply as you like.If you'd like to use the 20-pin ATX
power supply, please plug your power supply along with pin 1 & pin 13.
2
5
1
VCC
OUT
GND
IN
NC
Figure 2: Reference for 8 pin PWR12V.
GND
GND
+
+
12V
12V
1
2
3
4
Figure 1: Reference for 4 pin PWR12V.

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AMD 790GX User's Manual
Chapter 4 BIOS Setup Utility
BIOS stands for Basic Input and Output System. It was once called ROM BIOS when it was
stored in a Read-Only Memory (ROM) chip. Now manufacturers would like to store BIOS in
EEPROM which means Electrically Erasable Programmable Memory. BIOS used in this series
of mainboard is stored in EEPROM, and is the first program to run when you turn on your
computer.
BIOS performs the following functions:
1. Initializing and testing hardware in your computer (a process called "POST", for Power On
Self Test).
2. Loading and running your operating system.
3. Helping your operating system and application programs manage your PC hardware by
means of a set of routines called BIOS Run-Time Service.
4.1 About BIOS Setup
BIOS Setup is an interactive BIOS program that you need to run when:
1. Changing the hardware of your system. (For example: installing a new Hard Disk etc.)
2. Modifying the behavior of your computer. (For example: changing the system time or date,
or turning special features on or off etc.)
3. Enhancing your computer's behavior. (For example: speeding up performance by turning
on shadowing or cache)
4.2 To Run BIOS Setup
First access BIOS setup menu by pressing <F1> key after “POST” is complete (before OS is
loaded). After the rst BIOS be setupped(or loaded default values) and save, the <DEL> key
will be pressed if you will enter BIOS setup menu.
4.3 About CMOS
CMOS is the memory maintained by a battery. CMOS is used to store the BIOS settings you
have selected in BIOS Setup. CMOS also maintains the internal clock. Every time you turn
on your computer, the BIOS Looks into CMOS for the settings you have selected and
congures your computer accordingly. If the battery runs out of power, the CMOS data will
be lost and POST will issue a “CMOS invalid” or “CMOS checksum invalid” message. If this
happens, you have to replace the battery and check and congure the BIOS Setup for the
new start.
4.4 The POST (Power On Self Test)
POST is an acronym for Power On Self Test. This program will test all things the BIOS does
before the operating system is started. Each of POST routines is assigned a POST code, a
unique number which is sent to I/O port 080h before the routine is executed.

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AMD 790GX User's Manual
4.5 BIOS Setup — CMOS Setup Utility
4.5.1 CMOS Setup Utility
After powering up the system, the BIOS message appears on the screen,when the rst time
or when CMOS setting wrong, there is following message appears on the screen , but if
the rst BIOS be setuped(or loaded default values) and save, the <DEL> key will be
pressed if you will enter BIOS setup menu.
If this message disappears before you respond, restart the system by pressing <Ctrl> +
<Alt>+ <Del> keys, or by pressing the reset button on computer chassis. Only when these
two methods should be fail that you restart the system by powering it off and then back on.
After pressing <F1> or <Del> key, the main menu appears.
4.5.2 Control Keys
Press F1 to pop up a small help window that describes the appropriate keys to use and the
possible selections for the highlighted item.
Please check the following table for the function description of each control key.
Press F1 to Run SETUP
• In order to increase system stability and performance, our engineering staff is
constantly improving the BIOS menu. The BIOS setup screens and descriptions
illustrated in this manual are for your reference only, and may not completely
match with what you see on your screen.
• Do not change the BIOS parameters unless you fully understand its function.
Control Key(s) Function Description
←
/
→
Move cursor left or right to select Screens
↑ / ↓
Move cursor up or down to select items
+/ -/PU/PD To Change option for the selected items
<Enter> To bring up the selected screen
<ESC>
Main Menu - Quit and not save changes into CMOS Status
Page Setup Menu and Option Page Setup Menu - Exit
current page and return to Main Menu
<F1> General help
<F2/F3> Change Colors
<F5> Restore the previous CMOS value from CMOS, only for
Option Page Setup Menu
<F7> Discard Changes
<F8> Load Failsafe Defaults
<F9> Load Optimal Defaults
<F10> Save conguration changes and exit setup