Plz provive dell motherbord GX 280 windows vista driver.

please reformat you PC with win XP

Dell does not support Vista on your PC. No Vista drivers are available.

You can try downloading and installing either:
Device Doctor portable
or
SlimDrivers Free version

DOWNLOAD DRIVERGENIUS SOFTWARE FROM THE FOLLOWING LINK.IT WILL HELP YOU http://hotfile.com/dl/61173249/7fba4f4/Driver_Genius_10_Professional.rar.html

Did you install it to the factroy default installation or did you install windows anew? 

You need to install the Dell sound drivers. They're found on the dell home page or on your media that came with the Optiplex. 

Also, check the system control / administtration / hardware section to see if windows potted a problem with the hardware. 

the problem description is
Ithr
Smm mode is initializing the thermal probes.

problably the system is running at high temperature because of improper fan speed, so try to clear the nvram if its not working flash the bios if still the issue persists, replace the heatsink assembly and the motherbord.

There are different kinds of Optiplex GX P4, and they mount different kind of sound cards.

To ensure that you download the right driver, click on the link below and select the right Optiplex model, or enter the model number.

Use enter tag if you have the number, if that does not work, use select model>>Desktop PC>>Your Optiplex GX model.

Here is the link:Dell Drivers and Downloads

gx 280 sound driver

Hi,
Click Here to Download the drivers.
Thanks, PREM

download driver ''R145551.exe'' and install it for audio device to work. you can download this by typing the r145551.exe on google search for more details contact me [email protected]

Here you go.

http://support.dell.com/support/downloads/driverslist.aspx?c=us&l=en&s=gen&ServiceTag=&SystemID=PLX_PNT_P4_GX260&os=WW1&osl=en&catid=&impid=