OFFTEK 1GB Replacement Memory RAM Upgrade for Aopen AX4B-533 Tube (PC3200 - ECC) Motherboard Memory at Amazon.com
foone🏳️⚧️ on Twitter: "BTW the board is the AOpen AX4B-533 Tube, in case you'd like to research more. (I just realized I didn't say the name)" / Twitter
Sound section of the AOpen AX4B-533 Tube Motherboard
foone🏳️⚧️ on Twitter: "So yeah. This motherboard has a vacuum-tube based pre-amp for the on-board sound card, with the intention of giving it "true analog sound", something no other motherboard can match.
Retro Thing: Vacuum Tube PC Motherboard
Techware Labs - Reviews - AOpen AX4GE Tube-G
Sound card With vacuum tubes? | TechPowerUp Forums
Tube build with LIAN LI + Pentium 4 + GeForce FX5900 - RETRO Hardware - YouTube