Ask Electronics

trying to save an old motherboard, it's a Gigabyte GA-B75M-D2V. tried searching, got nothing usable back.

problem: no USB ports work - all the ones on the back, both USB 2.0 and 3.0, and all front ports. USB ports not working is common accross boards and manufacturers, but it's usually a subset, some work some don't and you can still use the thing.

ports have 5V, when the keyboard gets connected its leds light up for a second but don't stay on. the mouse's led doesn't light up when connected. neither are detected by the UEFI setup.

I got a PCI-Express USB 3.0 card, but that thing doesn't work for booting off of it or in UEFI setup, etc., only after boot from HDD.

otherwise, everything works - LAN, sound, audio, SATA, etc. I feel the platform still has a lot of life left, especially for my use cases.

this is not a software or settings issue, that's why I'm in "ask electronics" something is fried here and was looking for pointers what or where to look at.

no visible burns or busted caps and such. hoping it's something simple, any ideas what to look at?