I want to write what for Dosbox settings are needed to play 3D games like Duke Nukem 3D or Descent 1/2 properly. This might be different for other CPU´s but I can say for a Pentium 3 1000 Mghz with 8 MB VGA RAM and 256 MB RAM following settings: 1) Change the dosboxDuke3d.conf file. Write core=dynamic and cycles=25000.
Bellow only for Duke Nukem 3D:
Go into the folder: START->All programs->gog.com->Duke Nukem 3D->Network->START Client game. Call there setup.exe sinmply through write setup and enter and change the video mode from 320x200 to VESA 320x200.