I have a Hauppage TV tuner card that I use to get OTA TV and record certain shows. I’m pretty sure there are USB solutions, but if I remember, at the time I got this it was one of the only cards that my system supported or whatever caveat I was operating around.

This is a really interesting question. I remember a lot of very niche PCI (not PCIe) cards from the old days.

My current-day boring use-case: Multiple GPUs that have never once been used for gaming. One is an A2000 card that does video transcoding and tone mapping for Jellyfin. The other is an old Quadro card that handles encoding/decoding for my NVR.

• Second GPU for a VM
• SATA controller
• SAS controller
• SAS Expander

You can use a SAS controller or 10G ethernet card in the 16X slots. If your motherboard support PCIe bifurcation, you can get an adapter card to use 4 NVMe drives in a 16X slot. You can get controller cards for older interfaces like firewire, serial, and parallel that will use a 1X slot.

• AMD RX 6750 XT
• MELLANOX CONNECT-3 PRO 10GbE MCX312B-XCCT
• LSI 9211-8i D2607 LSISAS2008 SAS/SATA

my current usage:

on my desktop:

• RX 7900 XTX
• Wifi 6 adapter
• 10Gbit SFP+ NIC

on my proxmox server:

• RTX 3080 (passed through to Debian VM)
• 16 drive HBA (passed through to TrueNAS VM)
• GT 730
• 10Gbit SFP+ NIC

I’ve also used USB PCIe cards to get more USB controllers for picky USB devices like USB capture cards and audio interfaces.

MSI GeForce RTX 4090 SUPRIM LIQUID X

Additionally, I had a 3 port FireWire card that I used for digitizing old MiniDV camcorder cassettes. But I had to remove it because someone fucked something up in kernel 6.5, crashing the whole boot process after a few milliseconds.