Driver for Internal speaker in OptiPlex 780

I don't think there is an "internal speaker". You have to connect external speakers to the rear of the PC. The onboard audio port is green (#6) here:

If you have an add-in audio card, the onboard audio port will be disabled and you have to connect speakers to the card which will be elsewhere on rear of PC.

Dell doesn't support Win 10 on this model and is only offering an audio driver for Vista and Win 7. That driver may -or not- work with Win 10. http://www.dell.com/support/home/us/en/19/drivers/driversdetails?driverId=R297758&fileId=2731117736&osCode=WV64&productCode=optiplex-780&languageCode=en&categoryId=AU

You can go to the Intel Download site and use their Driver Update Utility to scan your system to see if it can find drivers for you:

downloadcenter.intel.com/.../Intel-Driver-Update-Utility

I added  Internal speakers first it was working but in window 10 driver not supported it.  :emotion-12:

Dell doesn't support Win 10 on this model and they didn't make your internal speakers, so have you checked the website for the manufacturer of your internal speakers to see if they have a driver that works with Win 10?  

Have you checked in Device Manager to make sure these speakers are enabled and set as the primary audio output device?

Might be helpful if you told us exactly what internal speakers you installed...

The internal business speaker doesn't work with windows 7 or 8 or 10 without installing the OEM soundmax driver.  Until you install that driver it won't work.  The Business speaker is OPTIONAL however.

Dell OptiPlex 780 Service Manual—Desktop Computer

Dell Optiplex 780 Desktop Speaker DP/N: D9901 Compatible With: OptiPlex GX520 GX620 320 330 360 740 745

https://www.amazon.com/Dell-D9901-Speaker-OptiPlex-GX520/dp/B013H9AJMY

D

That said the driver works fine with 7 or 8 or 10

All versions of windows work fine on the 780

the chipset and audio drivers are NOT native to windows.

https://www.walmart.com/ip/55080271

Description	Supported OS	Download
Analog Devices ADI 198x Integrated HD Audio, v.6.10.2.7280, A11 This package provides the Analog Devices ADI 198x Integrated HD Audio Driver and is supported on Optiplex 780 that are running the following Windows Operating System: Windows 7/Vista 64-bit.More details	Windows 7 64-bit Windows Vista 64-bit
Analog Devices ADI 198x Integrated HD Audio, v.6.10.1.7280, A11 Analog Devices HD Audio driverMore details	Windows 7 32-bit Windows Vista 32-bit

Description	Supported OS	Download
Intel ME5 Host Embedded Controller Interface Driver This package provides the Intel ME5 Host Embedded Controller Interface Driver and is supported on OptiPlex 760/980/755/780/960/780USFF that are running the following Windows Operating Systems: XP, Windows 7 and Windows 8.More details	Windows 7 64-bit Windows 8 32-bit Windows XP Windows 7 32-bit Windows 8 64-bit
Intel Serial Over LAN/Local Management Service Driver This package provides the Intel Serial Over LAN/Local Management Service Driver and is supported on OptiPlex 760/980/755/780/780USFF/960 that are running the following Windows Operating Systems: XP, Windows 7 and Windows 8.More details	Windows 7 32-bit Windows XP Windows 7 64-bit Windows 8 32-bit Windows 8 64-bit
Intel Chipset Software Installation Utility This package provides the Intel Chipset Software Installation Utility and is supported on Latitude, Optiplex and Precision models that are running the following Windows Operating Systems: XP, Vista and Windows 7.More details	Windows XP Windows Vista 32-bit Windows 7 64-bit Windows Vista 64-bit Windows 7 32-bit Windows XP x64

Description	Supported OS	Download
AMD Radeon HD3450 256M Graphics Driver This package provides the AMD Radeon HD3450 256M Graphics Driver and is supported on OptiPlex 580 that is running the following Windows Operating Systems: XP, Vista and Windows 7.More details	Windows Vista 32-bit Windows 7 32-bit Windows 7 64-bit Windows Vista 64-bit Windows XP x64 Windows XP
Intel GMA 4500HD/4500MHD Driver This package provides the Intel GMA 4500HD/4500MHD Driver and is supported on OptiPlex and Latitude models that are running the following Windows Operating System: Windows 7 (64-bit).More details	Windows 7 64-bit
Intel GMA HD Graphics 4500/4500M Driver This package provides the Intel GMA HD Graphics 4500/4500M Driver and is supported on the OptiPlex and Latitude models that are running the following Windows Operating System: Windows 7 (32-bit).More details	Windows 7 32-bit