So, might not be a new issue, just a reoccurence of an old one. It may not be related to the PoE HAT, just that adding one is making the issue appear in these two cases.

Do not expose the product to water or moisture, and do not place it on a conductive surface whilst it is in operation Power over Ethernet is a widely adopted standard that places power on the Ethernet cable along with the data. It has no effect on the data, so you won’t lose bandwidth by using PoE. There are various standards of PoE; this HAT uses the most common standard 802.3af, which allows delivery of up to 15W. This means that the HAT is capable of providing all the power needed for running your Raspberry Pi. You will need power sourcing equipment to power your Pi. This is either provided by your network switch or with power injectors on an Ethernet cable. If your Pi is running full blast with USB devices plugged in, the difference isn't as dramatic. But if you're like me, and you have some Pis running lightweight utilities like a web server or some monitoring utilities, doubling the idle power consumption isn't exactly ideal.Eben 3:53: And then there are modes where you put it on the single pairs, and you have to support both of those. Hopefully this coil whine or whatever it is doesn't indicate a deeper issue—I haven't had time to dig in much, but it's really unpleasant to hear in person. I've bought the POE+ HAT and now the RPi temperature is up from normal idle 50C to 68C. It is just a plain RPi with no peripherals. After I used an OS with kernel new enough to spin the fan, it is quite noisy. With

Eben 10:15: That’s very neat! Good. And how much more efficient is it than the previous design? Is it more efficient than the PoE+ design? Or is it — OK, now we have access to more than 6 watts of power. There are two obvious questions: How much power, and what can we do with it? To kill two birds with one proverbial stone, I grabbed a string of RGB LEDs and wired the voltage supply directly into the 5v rail. The PoE+ HAT has a wonderful feature — it adds a sysnode that tells you exactly how much current the HAT is providing. cat /sys/devices/platform/rpi-poe-power-supply@0/power_supply/rpi-poe/current_now It is used to power a Raspberry Pi via an Ethernet cable, provided that power-sourcing equipment is installed on the Ethernet network. The HAT also includes a fan that will cool the Raspberry Pi processor. Louder ADDA Fan: The new fan is also rated for higher temperatures and a longer lifetime, and the bearings used are a little noisier at high speeds. Tweaking the fan settings following the directions in my blog post Taking control of the Pi PoE HAT's overly-aggressive fan helps, though, because at low speeds, the new fan is actually a bit quieter than the old fan—32 dB on the PoE+ HAT, vs. 38 dB on the PoE HAT. Problems

Specification

Pull evenly so that it detaches from all the pins at the same rate; do not pull one end of the connector off before the other With the HAT mounted, I first tested the fan; the old HAT was a little annoying (but not too obtrusive) when it's fan was going full blast. Well, I compared the new ADDA fan (2.4 CFM at 12k RPM) to the old Sunon fan (2.2 CFM at 10k RPM), and here are the results: HAT 🎩 Unfortunately none of the published schematics from B+ onwards show any of the USB interfacing so you will likely need assistance from someone with access to the 'secret data' to pursue this further.

One thing that's a bit concerning: the pre-installed fan screw pictured above is too long. It's a 12 millimeter screw, and when you put on the HAT, the screw pushes against the camera connector.It’s embarrassing to have released a product with a bug like this, but it’s a lesson well-learned, and we will be improving our internal processes to prevent a recurrence. The solution There are definitely similar teething problems with this next-gen PoE+ HAT, and hopefully QA for the next board's launch is better. Eben 3:45: And there are PoE modes where you put the power on the spare pairs that are spare in some standards. Eben 2:39: Okay. So you have to advertise, you have a PoE-capable switch or a midspan injector, and you have to advertise to that that you are PoE-capable before it will give you the volts. So I don't understand what I'm doing to kill these Pi's. I'm wondering if anyone has any insight here.

This is a good write-up of an interesting bug. Stuff happens, and it’s always interesting to see how it’s handled – one of the best ways to understand something is to break it and work out what’s going on. A lot has gone right here.Eben 1:33: So there’s a simple mechanical reason, which is that that four-pin connector — what does the four-pin connector do? The maximum distance of PoE can transmit 100 meters from the switch or hub regardless of where the power is injected due to the ethernet cabling standards. If you wish to extend the maximum distance, you can make use of a PoE extender to further extend the maximum distance of up to 1200 meters. Source: Versatek Dominic 5:55: So the first PoE HAT was only a 13W product, and that had a much more conventional transformer on there. We’ve tested a variety of pass-through headers and can recommend the 2×20 pin header from Pimoroni and the 4-way risers from RS and element14.