I went to the Gigabyte website - GIGABYTE - Upgrade Your Life
I typed in the name of the motherboard in the search box on the front page - ga-8vm800pmd-775
I clicked on the link to the board it gave me in the search result
I clicked on the download link for the motherboard manual
I chose which country I wanted to download it from
It magically appeared on my machine ......
Or if you're asking for schematics rather than the actual motherboard manual, the only place you'll get this is directly from Gigabyte themselves and the chances of them releasing it to you are virtually zero