... What scenarios would 10GBit Ethernet be useful?
Apple's 10GbE socket also supports 2.5 and 5Gb/s .
10GbE switches tend to still be stubbornly a bit on the expensive side. There is probably more 2.5-5 stuff coming at what used to be 1Gb/E equipment prices. QNAP has a 2.5G switch.
https://www.qnap.com/en/news/2020/qnap-introduces-its-first-2-5gbe-network-switch
QSW-1105-5T has a street price under $100. ( so about $20/port ). Some midrange NAS devices are going to come with 2.5 ( that roll out has already started with QNAP and Synology in 2020) . The iMac with 10GbE of "overkill" for that equipment, but it also not a bottleneck either ( an iMac with 1GbE).
There is a catch-22 with 1GbE equipment being older and cheaper ( in part because largely refreshed old designs ). The "race to the bottom" on pricing of 1GbE is so steep now that network vendors are holding onto 10GbE to get decent margins. But the pressure to be faster than wireless is building. 1GbE just isn't going to cut it for setups that consist of 2020 and newer equipment going forward ( unless get to a congested WiFi zone in terms of traffic. Wired has much better performance gap when there is congestion over wireless. )
Widespread home networks with 10GbE may not arrive for a longer time but 2.5-5G probably will arrive sooner that the end of the "max service" lifetime of a 2020 iMac. (by 2026-7 that 2.5 swtich is going to be substantially more affordable). A couple of years before 2.5 goes standard on more than a few Intel reference design desktop boards. ( already some now. It is just going to grow from here. )
The "end" of 1.0 GbE is coming. ( frankly Apple could have made 2.5 standard for the price range of systems the iMac 27" is in. It is just a minor margin hit they probably don't want to do.... or "rock the boat" on design effort. )
P.S. 2.5Gb is coming but Intel has managed to stumble a bit on that too.
"..
Intel's i225 "Foxville" family of 2.5 Gbps wired Ethernet controllers have a design flaw that affects performance, according to an official advisory sent by Intel out to its motherboard- and OEM PC partners ...
The i225 family of 2.5 GbE chips are being extensively implemented in upcoming motherboard, desktop and notebook designs. The i225 "Foxville" family consists of the i225-V targeted at motherboards and notebooks with Intel chipsets that have integrated MAC; while the slightly pricier i225-LM has an embedded MAC, and targeted at other platforms (extensively found in high-end and upcoming AMD motherboards). ..."
Intel's i225 "Foxville" family of 2.5 Gbps wired Ethernet controllers have a design flaw that affects performance, according to an official advisory sent by Intel out to its motherboard- and OEM PC partners (notebook- and pre-built desktop manufacturers). There are no security implications of...
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