for classicube its a IBM PC300GL 6282-74U from 1996
Its specs are
Pentium MMX 200MHz
32MB of PC66 SDRAM
3Dfx Voodoo2 8MB
128MB of GLide cache
Intel i430vx (this is important cause it makes this things performance feel a bit slow)
16GB Quantum Fireball CX 5400RPM
Soundblaster VIBRA 16S CT2900
for internet either a 10Mbit 10-BaseT Ethernet card or a 3COM USRobotics 56k v.90 Winmodem
Running Windows® 95 OSR 2.5 with XUSBSUPP for actual USB support
There are pics of it running in the classicube discord or I can upload one here if anyone cares to see this thing running classicube