Xavier Ashe 2d ago
NoraBell 🏳️‍⚧️🌈
Anyone know where to get started on rebuilding a BIOS? I've got a HP dc5700 sff and I wanna use the ADD2 slot as a PCI-E slot. I don't see a reason it physically can't work, so it must be a limitation of the BIOS. This is my learning machine so if I kill it I kill it.

#retrocomputing #custombios
Mar 21 at 4:05pmWeb
Show threadBranch Predictor 2d ago
@NoraBell ADD2 port is SDVO (Serial Digital Video Out) and it's mapped into on-board graphics. It might look like PCI-E x16 but it's not. Modding BIOS won't work.
Show threadNoraBell 🏳️‍⚧️🌈2d ago
@branch300bpm

I had a feeling that's where this would end up.

Dremel to the 1x slot it is
Show threadPlaid2d ago

@NoraBell According to the docs, it's SDVO-only, not PCIe or ADD2.

It may be more than just BIOS limitations. HP could've pinned the slot in ADD2-N mode thus reducing the number of traces they had to route, etc.

Show threadNoraBell 🏳️‍⚧️🌈2d ago
@plaidtron3000 It supports SVDO and ADD2, just not ADD2-r or PCI-E proper. I decided to mangle the PCIe X1 slot and use the card in 1x mode, which will work once I get a SATA->PCI-e 6pin adapter to power the card
Show threadPlaid2d ago
@NoraBell Yeah, filing open the front of an x1 slot is a good solution when you need the slot but not a ton of bandwidth!