Have you tried higher resolutions?
If you don't force vsync, does that allow the game to start? If so, does it actually cause heat issues?
Try running the game in Win 9x compatibility mode (right click on the ..\SteamApps\common\divine_divinity\div.exe file, select Properties and switch to the Compatibility tab).
Try the Windows 8 Performance "Patch"
(works in Win 7 and 10, as well); that can help with some startup crashes.
You can try using the disk version of the configuration program, to set the game to run in Direct Draw mode. Rename or move the existing configtool.exe and NlsEng.dll files in the install folder, and extract the disk version
. Note that this will also reset the game resolution to what the disk version supported, but you can manually edit the config.div file to change the resolution back.
There is a configuration file edit to skip the intro videos (see here
), which could help.