It´s an inductor (as the other 5, with pads for parallel capacitors or resistors that are not populated).
You can replace it with a piece of wire for testing / to see if it´s the reason for the missing colour (blue).

To find the exact value of the inductor you need to measure one corresponding inductor of one of the other two channels (marked yellow).

But maybe someone here can tell you the value right away.

majestyk wrote on 2022-10-15, 10:44:

You can replace it with a piece of wire for testing / to see if it´s the reason for the missing colour (blue)

Thank you! I wonder though, would replacing it with a wire have potential to cause damage? If at worst it has bad image quality, then I'll try the wire for sure.

I also have no equipment to measure these. If no one has the specs, I'll get a bunch of different ones and eyeball it.

Signal quality of the blue channel will decrease a little without the inductor. But you won´t short or damage anything. You can short the pads with a small screwdriver for a second while the system is running to see if it fixes the missing blue issue. (Don´t short anything else with the screwdriver...)

Thanks! I think I'll solder a jumper wire. It's an old Compaq Deskpro with riser card for expansion slots, meaning this PCI card is face-down sideways in there. So no poking in there while it's running.

Holy s*** it worked. I shorted the pads and colors are normal. Thank you!

Now would anyone have a guess as to which particular one I should put there, or if I should just go for one of these sets and pick one that looks close enough:

I had a similar issue and the answer was either to just put a solder blob or a 5µH smd.

Thank you for the information, I'll order those.