Is there a difference between crimping an RJ45 connector onto an Ethernet cable in a (1) 10GbE scenario, vs. a (2) regular 100Mbps scenario, say? Can this be done by hand, or does this require professional tools, and hence one should not attempt this at home, but rather buy the proper length of factory-built Ethernet cables?
Are the RJ45 connectors different for such high frequencies, or can I use some of my old RJ45 I got laying around since the 100Mbps era?
Well. It depends.
100mbps, probably not. Gigabit. Maybe.
10gbe may work on cat 5e cables up to 55m
10GBASE-T , or IEEE 802.3an-2006 , is a standard released in 2006 to provide 10 Gbit/s connections over unshielded or shielded twisted pair cables, over distances up to 100 metres (330 ft). Category 6A is required to reach the full distance and category 5e or 6 may reach up to 55 metres (180 ft) depending on the quality of installation.
You can crimp the cables yourself, ideally you need cat6a crimps and cables and a high quality crimper and you need to keep the twists as twisted as possible, and as short as possible etc
Ie âquality of installationâ
But at the end of the day 5e does work, and thatâs gigabit.
100mbps may just be cat 3 or not have all 4 pairs!
Thanks. I got CAT 8 cables everywhere. So youâre saying that I should look for gigabit-or-better-rated RJ45 connectors? Do RJ45 connectors come with CAT ratings? Are there RJ45 CAT 7 (or better) connectors?
You should probably use Cat 6A or better crimps
The difference between CAT 5, 6, 6A, 7, and 8 are quite simply the twists per inch in the cable pairs. The more twists, the better the signal rejection or some call it balanced. I didnât even know CAT 8 existed, now I know and CAT 8 costs more because there is more copper per foot in a CAT 8 cable than a CAT5 cable.
The end connectors are the same although one would hope for a better quality connector for a higher priced cable. CAT 3 was only 3 wire pairs I think, wow itâs been a minute.
Ultimately you can use CAT 8 at CAT 5 or greater frequencies (speeds).
As for your original questionâŚ
There are special tools that you can buy in a typical hardware store or over the internet, they are not expensive. There are at least two types Iâve seen, one is the typical cheap termination and then you have a âPass throughâ crimper as well, which also work on normal end. Now the Ethernet connectors themselves have different variations and some are significantly easier to use than others. My preference in the Pass Through Ethernet connector (Google it). You push the wires though the connector and out the front, you can double check you have it wired in the correct order (have no fear, we all screw this up a few times), and when you crimp it, you know the wire was fully in the connector.
Data centers or any place that has an IT department make their own cables on site, in the moment. If they need a 150â cable, they string it up and terminate the ends and plug it in. Sometimes they test the cable too but most do not as it is a simple thing to cut an inch off and terminate the cable again.
As @Stux said, Cat 5e up to a certain length is fine but too far and you have signal ringing. I had to deal with this on submarines and running very long cables from the fire control center, to the missile tubes. These were not Ethernet at the time but they were twisted pairs an where I learned about this stuff.
Lost of people make their own cables, it isnât rocket science 
If you have to make a dozen custom length cables, Iâd say it is worth it. Odds are you will use the tool again. Oh yes, I have the crappy tool for home. If I ever need to make more cables, I will buy the good one. It saves a lit of grief.
Hope that helps.
Two pair. Which is why the answer to OPâs original question is âno, not reallyâor at least, not necessarilyââbecause so-called Fast Ethernet only needed those two pair, while gigabit and up needs all four pair. But compared to gigabit, there isnât likely to be much of a difference.
I donât ordinarily terminate my own patch cables, though; my understanding is that the stranded wires called for are harder to deal with, and patch cables are cheap. But in-wall runs terminated to keystones? All the time.
What do you guys think of these new flat Ethernet cables? Are they any good? All reviews I have seen are more or less stellar.
If they meet the cat specs, and you have a need that justifies the typically higher cost, why not? Iâm thinking the arrangement of the individual conductors might make it harder to terminate yourself, though, and I donât recall that Iâve seen bulk cable available.
Personally, Iâm using fiber for 10G[1], which is considerably smaller than even the flat ethernet cables. But if you want to use copper, and itâs over fairly-short distances, copper âworks,â for certain values of âworks.â
with one exception, that being from my UGREEN NAS to the switch, because that NAS came with onboard 10 GbE using RJ45 âŠď¸
Iâm surprised youâve seen good reviews for flat cables - Iâve personally only seen the opposite.
Unless you got a really short run that is also very tight, I donât see why youâd bother with them. Why not use a normal CAT6a wire? Itâll be more likely to be in spec & (possibly) cheaper.
Hopefully someone from iEEE and/or TIA will chime in & tell me why Iâm outright wrong (or who knows, maybe even right) & youâll get a more in-depth explanation than should be reasonably possible on the complicated nonsense that goes into something as âsimpleâ as a wire.
As long as you get something within spec & use them within that spec theyâll just work. If I have a 1 meter run between two 10gig ethernet nics; there would be absolutely no performance difference between cat6 and cat8. Both would work just fine at that distance & both would throughput 10gig speeds without any issue. Theyâll be equivalent to each other in terms of performance & theyâll be no benefit to spending the extra money on cat8 in this specific scenario.
At the same time, wires are stupidly complicated, because if you donât have something that actually meets the spec (or you got far outside the spec), then youâll have random & hard to diagnose issues caused by the silliest & likely cheapest part of network; the wire.
If you have CAT5e RJ45 connectors, sometimes with CAT6 or CAT6a the sheathing is a little thicker and CAT6 and 6A connectors are designed to accommodate the thicker sheathing but, I have used CAT5e RJ45 connectors on CAT6 and 6A with no issues. The connector itself does not affect signal, the brand/quality of the connector can have an affect on signal, ease of installation, specifically how the pins âbiteâ on the wire after crimping.
Technically CAT7 is for 10GbE but for short distances CAT6a will work just fine. CAT5e would be fine as well but crosstalk can be an issue.
It is not difficult to do, you just need a set of crimpers and a cable stripper. Klein Tools, Ideal and South Wire are a few reputable companies that sell them. Not sure what region you are in so you may have different brands available. A few YouTube videos and following the instructions included with the crimper should do just fine. Just ensure you use the same standard on both ends, i.e T568A or T568B, B is most commonly used in North America.
