Enigmas Youtube channel Youtube channel covering old DOS demos and games.
SID-Spielers page (german) SID-Spielers page with Commodore 64 music CDs, all former magazines and disks from CompuTec Verlag (Magic Disk 64, Golden Disk, Game On, Input64).
SID-Spielers Twitch video channel Twitch channel of SID-Spieler with history of his broadcasts
AmoRetro (german) Another website for friends of old computers. Has a decent hardware gallery and more...
VOGONS forum A forum related to the development of the DOSBox emulator. However it has also a subforum with discussion about real old hardware.
DOSforum A forum related to hardware and software from times when DOS was the most used PC operating system.
Anandtechs chipset guide Chipset guide from Intel 430FX to Intel 440GX including chipsets from other vendors by Anand Lal Shimpi (Anandtech). A good overview to compare the feature sets. Note that on specific mainboards the actual implementation may differ, like when there are less memory banks soldered than supported by the chipset.
Vintage 3D Benchmarks, Tests and background stories of vintage 3D accelerators. The page has also some good overview tables of cards technical values.
Fabien Sanglards blog Technical background for old game engine and scene demo code as well as old graphics accelerator such as Rendition Verite.
Forum 64 German community forum for Commodore computers, with focus on C64.
Gonas DOS game compatibility matrix Gona tested the most common old graphics cards for problems in DOS games. This incredible work is condensed in this table. If you want to choose a graphics card for DOS gaming check it out.