I'm on day 18 running my C4 stick on my C5 (only 11 days shown on graph because I'm now graphing the data out of Hub Information device vs. old way). No GUI slowdowns, memory is decreasing but it's dropped below 150k and didn't seem to impact anything. No CPU spikes that I can tell. If I was still running the same devices and stick on my C4, it would have crashed several days ago.
Only thing "new" on my C5 is the Hub Information driver as I was afraid the device was too "chatty" to put on my C4. But I'd rather graph the data from the Hubt information device via Maker-API/node-red and account for the "time" to get the information vs. querying URL's on the hub itself which doesn't account for load and such. Perhaps that's not a valid argument since Hub information is doing just that...
What @672southmain posted. But there is a line command for it. Sorry, don't know it off the top of my head but it's in the forums somewhere. Following many threads the C7 runs considerably cooler.
There probably isn't a "real" difference... I'm thinking it's a difference of a) sensor or b) proximity or c) CPU version. Very slight design differences/choices in how to manufacture the PCB. Perhaps one CPU has a temp sensor in the die, while another CPU is designed for it to be external.
They will sit in a somewhat narrow range however.
C-3's and C-4's have a heat sink on the CPU, but it's coupled through a piece of conductive material. The heat sink is screwed to the lid and the PCB is on the bottom piece of the case. Between is a blue heat conductor that is somewhat squishy. When I initially saw the temp differences in the reports between the C-3/4 and C-5/7 the image of that blue conductor came to mind.
A C-4 from oh so long ago. The blue stuff (circled) is the material that transfers the heat from the CPU (square) and into the aluminium heat sink in the cover. (Maybe it's clear, but the CPU's impression in the blue material is offset. It isn't centered on the CPU. When I put it back together after taking these pics, I put the blue stuff on the CPU first and then jammed the lid back on. This particular hub is "retired" at the moment... I may never find out if adjusting the blue stuff improved anything. )
I noticed that when I opened my C4 as well. However the purple pad is really thick and the "heatsink" is not aluminum. So any cooling will not be all that effective.
The thought came to mind that the "heatsink" wasn't for thermal management but a weight to keep the unit from being overwhelmed by the cable weight.
I don't know about the C7 internal cooling, but on my C7 bottom is warmer that the top (87 vs 83 °F)
I think a die temp of 194°F (90 °C) is well out of the expected range.
If one wanted to, a simple test would be:
Turn the hub off for 2 to 3 hours,
Restart reading the temperature as soon as possible.
Long ago, someone else mentioned the squishy pad and that caused me to open mine and take a look. I remember that post mentioning the name of the material, but I haven't been able to dredge it up from memory.
You could easily be correct regarding the value/use of that chunk of metal. I just popped it open again and it is ferris so not aluminium.
Not great as a thermal sink, but better than air
Can't measure junction temps, but 90C die temp (if that's the reading we're getting) leaves some headroom...
All semiconductors have some specified safe upper limit for junction temperature (TJ), usually on the order of 150°C (sometimes 175°C ).
Yes but, the temperature limits are largely determined by the thermal stresses in the die/package. An engineer from International Rectifier told me their MosFets will run a long time at 175°C (not near the temperature when the semiconductors start to change back to a chunk of silicon.)
What causes the failures (for the most part) is thermal cycling. This is where the stress is, especially in a power semi.
Yea.. cleeeeeearly you and I could fall into Engineer Speak too easily but I try my best to avoid that I remember that someone's going to read this in a year and I've gotten like or two a year after I wrote a post... read that antique post and wonder who wrote it. (I did, but it doesn't sound like me.)
When I was having issues with my C4 @gopher.ny could tell the CPU was being throttled due to heat. Thus why I moved my stuff to a C5 and haven’t had any of the same issues.
It's a good point and it happens that I have a small fan near to a pair of my Hubs. The two hot ones coincidentally. I think I'll move things to have the fan directly 'cool' one of them and follow the temps.
OK, first, the initial values...
Above is a screen cap of 4 hubs and just one has the fan, 3" away... this one:
That was then, this is now and my initial reading just a few seconds before adding the fan was 65 degrees C because today is a rather hot day so ambient is higher.
2 mins after adding the fan, the temp dropped to 58 degrees C and it's currently, 40 minutes later and the temp seems stable at 54 degrees C. I think from here on, temp will track ambient.
