HELP PLEASE new computer but no sound

ok so i bought a new computer and i love it. It is a

CyberpowerPC Gamer Ultra 5212 Athlon 64 X2 5200+ 2GB DDR2 250GB NVIDIA GeForce 8400 GS Windows Vista Home Premium - Retail. I bought it off of newegg. 

Motherboard is Chipset NVIDIA nForce 560 SLI Chipset
Motherboard Name ASUS M2N SLI

It has a 7.1 sound built into the mother board but the problems is i get no sound out of the output in the back of the computer. I have a headphone jack on top of the computer and i get great quality sound out of it. But I am stuck, when i plug into the jack on the back of the computer i have to turn my sound way up and I get a fait sound of my music. This happened to some other people on new egg on the reviews they said that they fixed it but they don’t say how to. Does any one got any ideas???

Thanks

Go to Yast - Hardware - Sound
In the screen, lower right -‘other’ button - select Volume
set sliders up to max

now try

can we just check which operating system you are asking for advice on:

you say:

CyberpowerPC Gamer Ultra 5212 Athlon 64 X2 5200+ 2GB DDR2 250GB NVIDIA GeForce 8400 GS Windows Vista Home Premium - Retail.

and

and i love it.

??

General Spec
Brand CyberpowerPC
Model Gamer Ultra 5212
Recommended Usage Gaming
Processor AMD Athlon 64 X2 5200+
Processor Main Features 64 bit Dual Core Processor
Memory 2GB (2x1GB) DDR2 800
Hard Drive 250GB SATA-II 3.0Gb/s 8MB Cache 7200RPM HDD
Optical Drive 1 20X DVD±R/±RW Dual Layer Drive
Graphics NVIDIA GeForce 8400 GS 512MB PCI Express Video Card
-1 x DVI
-1 x VGA
-1 x S-Video Out (HDTV Compatible)
Audio Sound card - Integrated
Keyboard 104 PS/2 Keyboard
Mouse Optical Wheel PS/2 Mouse
Operating System Windows Vista Home Premium
Special Features Apevia X-Jupiter Jr w/ 420w Power Supply
Motherboard
Chipset NVIDIA nForce 560 SLI Chipset
Motherboard Name ASUS M2N SLI
CPU
CPU Type Athlon 64 X2
Installed Qty 1
CPU Speed 5200+
CPU Main Features 64 bit Dual Core Processor
Graphics
GPU/VPU Type NVIDIA GeForce 8400 GS
Graphics Card NVIDIA GeForce 8400 GS 512MB PCI Express Video Card
-1 x DVI
-1 x VGA
-1 x S-Video Out (HDTV Compatible)
Graphics Interface PCI Express x16
Memory
Memory Capacity 2GB DDR2
Memory Speed DDR2 800
Memory Spec 1GB x 2
Memory Slots (Available/Total) 2/4
Hard Drive
HD Capacity 250GB
HD Interface SATA
HD RPM 7200rpm
HD Spec SATA-II 3.0Gb/s 8MB Cache
Optical Drive
Optical Drive Type DVD±RW
Optical Drive Spec 20X DVD±R/±RW Dual Layer Drive
Audio
Audio Chipset Integrated
Communications
LAN Chipset Integrated
LAN Speed 10/100/1000Mbps
Front Panel Ports
Front USB 4
Back Panel Ports
COM 1
LPT 1
PS/2 2
Video Ports 1 VGA, 1 DVI
TV Out 1
Rear USB 4
Rear IEEE 1394 1
RJ45 1 port
Mouse
Mouse Type Optical Wheel PS/2 Mouse
Keyboard
Keyboard Type PS/2 Keyboard
Manufacturer Warranty
Parts 1 year limited
Labor 1 year limited

what is “Yast” are you saying to go to setting hardwear and then to sound and click on sound then on to playback and turn it up to max.

Dude, now I’m confused - are you actually running Suse Linux? Or M$ Vista. If your running M$, go to their forum, you should get better advice.
…Oh, but hang on… do they have a forum like this?