What are the rubber circles for on the back of my pc case? Should I just leave them like that if don't have a need for them? Or are they likely to let I'm dust into the motherboard?
Edit: thanks for all the replies, so just for water cooling I have no need for.
It is probably an old case design. In the early water cooling days, there would be separate watercooling units that sat outside the case. The grommets were so you could pass your tubing through.
I wouldn't really worry about the dust tbh, you will wind up having to clean it regardless.
Not just for water cooling. It's for cables that pass in or out too.
Such as?
Edit: I mean you can contrive something if you're MacGyver but there's no remotely standard use case for that.
Kvm
Anything that doesn't have an external connector or some way to mount one. One example would be if you were using a USB Wi-Fi radio and wanted to connect it to the internal USB connectors but you'd need to pass the antenna to the outside of the case.
There were some old PCI cards that were very badly designed, and they required things plugged into them from inside the case, or they needed to plug into things on the motherboard. I had card that controlled Cold cathode tube lighting that could also connect to audio to sync to the music that worked that way
But, the actual answer is that the grommets are for old-school water-cooling.
Such as sata cables for quickly hot plugging hard drives you are testing/inspecting/cataloguing and don’t want to open the whole case between each drive, or leave the case open.
Mine has an 3 position exrernal fan switch for manual control, cable comes out those holes. Also useful for direct header usb that you run an extender cable out to another device.
3 position? all of my fans get controlled in software from 0-100% speed, reacting based on temperature
While that is an option for anyone, its not something I wanted. Mine is cube with 200mm fan. The lowest setting is fine for the thermals, but if I'm video processing I will toggle to high, but for voice over or a phone call comes in I drop it down low. The random up and down of the fan if left to its own device creates a noise I don't want to deal with.
This is it! Old water coolers
Specifically, these are for being able to pass in the tubing when your computer overheats playing Counter-Strike 1.5 so you pull apart your 50cc moped so you can bolt the moped radiator to the side of the case since it doesn’t fit inside. At least that’s the only use I’ve actually seen in practice.