Hmm, it should still detect but at 1x perhaps. That's one of the in-line capacitors used for the differential pair signals of PCIe channels.

This gives some good clues on replacement: https://forums.developer.nvidia.com/t/pcie-ac … r-size/269319/3
Putting a 100nF 0603 capacitor there should get it communicating again.

For replacing small stuff like that, my preference at this point is to use a soldering iron that can cover both ends of the capacitor. Clean up the remains of that cap on both pads being careful to avoid shorting the adjacent cap. Put the new cap in place and hold it with tweezers, solder down one side of the cap.
Then hold the iron up to both sides of the cap and push some flux-core solder into the tip, which will nicely reflow both sides of the cap.
Usually ends up looking quite tidy 😀

AC coupling, Intel says ~200 nF. You can desolder and measure one next to missing spot.

Thank you both for your advice, I have a good idea of what I am looking for.

I think I will have to borrow some kit to try a repair, the iron I have might as well be for clothes, it's about as suitable for this fine work.

Thought for the day: A clothes iron is a hotplate that they built the wrong way up.... probably not ideal in this situation though as there are components on the backside also? Also gotta watch the set point wandering 30 degrees up and down with the slow thermostat click clack, okay if you keep an eye on it with IR thermometer.

But MacGyver time, you just got dropped off by the floatplane at the way north fishing camp, it comes back in 2 weeks, only comms is satellite internet, or WAS satellite internet until you bust the NIC that needs to talk to it. Hunting round the cabin you find tweezers and an old razor in the washroom, in the boat shed you find a 50W iron and solder which is for putting the unobtainium connectors on the new condensors that the fishing boat motor, that is older than your father, needs....

... I would do this... cut two tiny "coins" off the end of the solder with the blade from the razor, find a likely donor component, take it off with the razor or the iron just held right on it briefly.... then set a little "coin" of solder on each pad, and sit the component across them... now either you've got a super steady hand or you prop or tie or wedge the soldering iron in place until it's hovering a mm off the top of the component, and just watch and wait, let the radiant heat cook it up to temp and settle down onto the solder.