With the advent of affordable 2.5 Gbit, 5 Gbit, and 10 Gbit consumer networking gear, more and more people are taking advantage of these higher networking speeds, with [This Does Not Compute] having used 10 Gbit SFP+ modules over regular Cat-5e copper to connect to a NAS in the next room. Only problem was that after a while these SFP+ modules began to start dropping frames. On taking a closer look at these modules, he found that they were running pretty hot: 40°C while idle. A teardown of one of these modules showed severe discoloration due to heat.
Inside these 10Gbit modules is the Marvell-branded Alaska X 88X3310/40P PHY, which despite the ‘low-power’ claims have a metal heatsink glued onto the actual IC and thermally coupled to the module’s metal enclosure. The other side of the PCB was quite discolored, further indicating how hot these modules run in operation. Some digging revealed that this can go up to around 2.5 watts.
Perhaps the most fascinating part of this teardown is the discovery of an 8051-based MCU that’s responsible for telling the switch the module is put into that it is a 30-meter multi-mode fiber module, presumably for compatibility purposes. It’s definitely an interesting feature of these FS-branded SFP+ modules.
These old modules were replaced with Wiitek-branded modules that are supposed to use only up to around 1.5 watts in operation courtesy of a newer chipset, in the hope that these wouldn’t fry themselves. At idle these do however still run at 30 °C. As noted in the comments, it might be a good idea to have active airflow over high-speed networking gear like this, as they generally can get pretty hot and sometimes crispy.
The final solution for the video’s networking problem was to just run single-mode fiber to the room and use appropriate SFP+ modules for that, also because these run noticeably cooler. If you still have room in your cable ducts, that would seem to be the optimal solution.
The newest option which uses very little power and stays cool utilizes the realtek RTL8127 chipset. I am using one with the sfp+ cage in one of my PCs and it has been fantastic so far.
Please just don’t use copper 10G (10GbaseT) modules in any SFP port which doesn’t specifically claim compatibility with 10GbaseT. The copper rj45 modules all use a lot more power and generate more heat than fibre or DAC. Regardless of FS compatibility tricks, if it doesn’t support any copper modules, then it won’t have the power and heat dissipation capacity required.
It’s best to buy NICs and switches with integrated copper multi-gig ports.
The cards with integrated rj45 ports sometimes run hot too, depending on the chipset. I may or may not have accidentally fried a PCIe port on a Dell VRTX this way…and also melted the little plastic shields dell had between the ports. Fan offset is turned up now 🤪
Just one tiny kink in the cable and power consumption can go through the roof. Avoid 10GbaseT if possible. Fiber is the more reliable and often cheaper option.
I was overheating my mini PC that had two SFP+ cages and was my Linux firewall with 10G modules.
Swappi to short DAC runs was cheaper and used significantly less energy. Stayed cool. I even added a 25 Gbps card with two SFP ports and used DAC with those too. Great choice. No more heat issues in that tiny chassis.
Fiber is also cheap for interconnects of my switches. Including a 100 meter run to my guest house. Less than $100 for that run including both modules.
I’m slowly getting away from RJ45 wherever I can, but most of the house is 6A or 7, so I’m stuck there.
I wonder if the end is near for traditional Ethernet ports and patch cables.
There are pasive SFP to copper cables… why you adding aditional layer in converter?