Welcome to the Dell Community  @Nabpo 

This error message occurs due to driver and OS version incompatibility. 

Note: You cannot install a 64-bit driver to a 32-bit Operating System and vice-versa.

What version OS are you running "XP, Vista, W7 etc"

Is it 32Bit or 64Bit???

What model video do you need drivers for???

Best regards,

U2

790 drivers are specific.

https://www.dell.com/support/home/us/en/04/Drivers/DriversDetails?driverId=T80W8

You download the cab file and save into my documents folder.

You then extract the CAB contents in the mydocuments folder using 7zip.

https://www.7-zip.org/download.html

https://downloads.dell.com/FOLDER01299327M/1/790-win7-A06-T80W8.CAB

Once extracted you right click on any yellow !  in device manager and say update from my pc instead of from the internet.

Category ReleaseID DeviceDescription DellVersion VendorVersion

@speedstep 

Will all these drivers (not just video) work on a 790 MT which has win 10 pro, 64bit installed?

I noticed they are win 7, but maybe the same?

@donm4599x 

Most of your W10 drivers will be automatically loaded while installing W10.

If needed you can use your W8 drivers found at your driver support page.

https://www.dell.com/support/home/us/en/19/product-support/product/optiplex-790/drivers

If after that you still need any drivers you would need to go directly to Intel or to the hardware manufacturer.

Use the hardware ID to search Google and find drivers you may need.

https://m.wikihow.com/Find-Hardware-ID

Product support for OptiPlex 790:

http://downloads.dell.com/published/pages/optiplex-790.html

Regards,

U2

Thanks.

So there is no cab file like speedstep posted? I was hoping to download it so I would have all the drivers on hand in case of problems down the road.

@donm4599x 

There are no Dell W10 drivers on your support page because your model was not sold with W10.

So there is no W10 driver pack for your desktop.

That's why you must rely on Microsoft drivers.

That includes W8 and W7 drivers if needed.

Last resort is going to the Hardware manufacturers website to download drivers.

Regards,

U2

Thanks! I guess I can't do what I wanted if the win 7 data cab won't work 

@donm4599x 

For reference if needed???

https://www.dell.com/support/article/us/en/19/how13322/dell-family-driver-packs?lang=en

Best regards,

U2