I also do think this is massive overprovisioning, starting with the 5Gb plan, but I will suspend that. How do your computer room machines connect to your existing switch? If you have existing wall ports for them then you can get away with one 10Gb switch in the garage. If you only have one wall port in the computer room then you are correct in that they will need a switch. That switch’s single 10Gb uplink to the garage could become a bottleneck but I wouldn’t worry about that since your internet connection is only 5 anyway.
I also do think this is massive overprovisioning, starting with the 5Gb plan, but I will suspend that. How do your computer room machines connect to your existing switch? If you have existing wall ports for them then you can get away with one 10Gb switch in the garage. If you only have one wall port in the computer room then you are correct in that they will need a switch. That switch’s single 10Gb uplink to the garage could become a bottleneck but I wouldn’t worry about that since your internet connection is only 5 anyway.