I'm going to re-write my previous post as it was a mess of updates and edits:
I have done a quiet(er) fan swap on my LB6M, running Brocade firmware. I got 3 x Noctua 40mm x 20mm 3-pin fans for the main switch. I wanted 4-pin PWMs but they were out of stock for a few days, so in my impatience I got 3-pin thinking they'd be fine. How annoying; they're not.
The core problem is this: most of the time (but not all) with 3 x 3-pin fans connected, show chass gives me no temperature information, and always shows all fans as OK:
EDIT: as per next post, this is not specific to me, or Brocade. I've found an old post where another guy had the same problem when using 3-pin fans, according to his "show environment" output on FastPath, which showed Temp = 0 Celsius. And further, my testing has confirmed that manipulating the fourth pin does weird things to the temp monitoring of show chass.
If I plug in 3 x 4-pin PWM fans, show chass immediately works as normal. Tested both with the original 3 x 40mm fans, and also three Noctua 4-pin PWM fans. When 3 x 4-pin fans are connected, I get working temperatures and working fan detection.
But what is very strange is that the first time I connected my 3 x 3-pin fans, I got working temps, and over multiple power cycles. I connected the three fans, I booted, I checked show chass, it had temperatures as normal. I then power cycled several times while changing the PSU fans, and every time I booted I checked show chass and it was always working fine.
Once everything was setup, I let the switch idle for about an hour, monitoring the temperature. I then decided I would test temperatures at a lower fan speed, using the Noctua low-noise cables. I swapped all three Noctua fans out with their Low Noise Adapter (LNA), and power cycled.
This is when the problem started - after that boot, and most every subsequent boot, I got no temps in show chass. And if I disconnect a fan, it still shows as "Fan OK".
Since then I have tried the following without change:
Then there's the question of why it worked perfectly the first time I connected everything up, and for at least an hour afterwards, and then almost never worked again after I first connected the 3 x LNA cables. But then did work twice more, very briefly, after I swapped 1 x original fan for a Noctua.
Maybe there's a way to connect the fourth pin to something, to 'fool' the motherboard, given it seems to be really affected by not having something on that pin?
Thanks in advance.
I have done a quiet(er) fan swap on my LB6M, running Brocade firmware. I got 3 x Noctua 40mm x 20mm 3-pin fans for the main switch. I wanted 4-pin PWMs but they were out of stock for a few days, so in my impatience I got 3-pin thinking they'd be fine. How annoying; they're not.
The core problem is this: most of the time (but not all) with 3 x 3-pin fans connected, show chass gives me no temperature information, and always shows all fans as OK:
Code:
Fan 1 ok, speed (manual): 1<->[[2]]<->3
Fan 2 ok, speed (manual): 1<->[[2]]<->3
Fan 3 ok, speed (manual): 1<->[[2]]<->3
Fan controlled temperature: 0.0 deg-C
...
Exhaust Side Temperature Readings:
Current temperature : 0.0 deg-C
Warning level.......: 80.0 deg-C
Shutdown level......: 90.0 deg-C
Intake Side Temperature Readings:
Current temperature : 0.0 deg-C
If I plug in 3 x 4-pin PWM fans, show chass immediately works as normal. Tested both with the original 3 x 40mm fans, and also three Noctua 4-pin PWM fans. When 3 x 4-pin fans are connected, I get working temperatures and working fan detection.
But what is very strange is that the first time I connected my 3 x 3-pin fans, I got working temps, and over multiple power cycles. I connected the three fans, I booted, I checked show chass, it had temperatures as normal. I then power cycled several times while changing the PSU fans, and every time I booted I checked show chass and it was always working fine.
Once everything was setup, I let the switch idle for about an hour, monitoring the temperature. I then decided I would test temperatures at a lower fan speed, using the Noctua low-noise cables. I swapped all three Noctua fans out with their Low Noise Adapter (LNA), and power cycled.
This is when the problem started - after that boot, and most every subsequent boot, I got no temps in show chass. And if I disconnect a fan, it still shows as "Fan OK".
Since then I have tried the following without change:
- Fiddling with wires/checking connections etc
- Power cycling five, six, seven times in a row, with gaps in between
- Pulling and re-plugging the fan tray
- Unplugging each of the three Noctua fans in turn, to the point of having 0 fans connected
- Booting with 1 x original fan + 2 x Noctua
- Booting with 2 x original fan and 1 x Noctua
- Booting with 1 x original fan or 2 x original fan - which is really weird, because this is a standard failure case! (EDIT: Ah, it depends which fan is connected. If the one nearest the PSU is connected - fan 3 - I get temp figures and that one fan behaves normally; if it's not, then any connected fans run at 100% speed and no temp figures are shown.)
- Putting in the fan tray from my LB4M, which is the same model number, and trying the 3 x 3-pin Noctua fans in that instead.
- As mentioned, having 3 x 4-pin PWM fans always seems to work
- 3 x 3-pin worked when I first put them in, and continued to through a couple of power cycles
- After that, I twice got it working again by:
- Running with 1 x original + 2 x Noctua, booting = not working
- Replacing the 1 x original with the third Noctua and booting again = then it worked.. but only to the next power cycle
- This sequence worked twice in a row, but then the third and subsequent time I tried it, it stopped working.
Then there's the question of why it worked perfectly the first time I connected everything up, and for at least an hour afterwards, and then almost never worked again after I first connected the 3 x LNA cables. But then did work twice more, very briefly, after I swapped 1 x original fan for a Noctua.
Maybe there's a way to connect the fourth pin to something, to 'fool' the motherboard, given it seems to be really affected by not having something on that pin?
Thanks in advance.
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