Main question: These are backwards compatible, yes? If I stick a Cat 8 in to replace a Cat 5, it may or may not work better but it will not do harm?
The specifics:
I’ve decided I need to move my router from the basement to the main floor to increase laptop online performance (laptop is on main floor). I have in place an old Cat 5 cable that I could run from the main floor router to the basement desktop PC - I did a trial connection and this worked but slowed down the basement PC considerably.
The existing cable looks a little rough and is a good bit longer than it needs to be.
Next question: Which Cat should I get for the upgrade?
I’m in the middle of a household wiring project, and I went with Cat6 FTP. The FTP means it has a foil shield around the entire bundle of 8 wires.
I considered Cat7, but with my small house, decided at the distances I’m using, it would offer no advantage over Cat6. Cat6 FTP is more than capable of transmitting 10 gigabit speeds up to 100 meters, and I don’t even have any use for 10 gigabit yet, let alone more. I did decide to run conduit to make it easy to upgrade in the future, though.
One thing you have to take into account is how much thicker and more rigid Cat6 and above are. They have this plastic “star filler” in the middle that keeps each of the four twisted pairs separated from the others:
Between that and the foil shield, the Cat6 FTP I got is over 1/4" in diameter, and very stiff. It doesn’t flop around like Cat5 does. This makes it significantly more difficult to work with in terms of fishing it through walls, or being able to drill holes large enough if you need to run a bundle of them. Cat7 would be even worse.
I suppose if you were willing to spend the extra money, Cat7 wouldn’t be out of the question, if you want to make sure you’re future-proof for a very long time, but IMO Cat8 would be overkill.
If they get to 0.375-inch thickness, then we’re back to good old Thick Ethernet cables. Progress!
To the OP: There are several variations of each “Cat”. So there are Cat 7 cables with TERA connectors, for example, rather than the so-called RG45. (There was some issues between standards bodies. The “standard standard” actually jumped from 6/6A/6e to 8 to avoid confusion.)
Cat 8 is expensive and really for specialized installations like where electrical noise is a problem. A regular house shouldn’t be in that realm. Cat 6 is basically the “almost sweet spot” for high speeds without paying an arm and a leg. 5e is good enough for gigabit and that will transfer files pretty fast, IME. Quite a bit faster than, for example, than needed for HD compressed video watching.