--- Mod note ---
Please keep this thread for the specifics of the C2750D4I board, as used in the FreeNAS Mini. For general C2000 LPC clock degradation discussion, use this other thread instead.
-------
Hi all,
I just wanted to report back my findings after my Asrock c2750d4i board froze one day after about 4 years of flawless service with ESXI (and freeNAS initially).
The unit restarted fine but froze again after a couple of hours and then it wouldn't start. I could access the IPMI interface but that only displayed 3 voltages.
After disconnecting everything and tested the PSU, and a lot of googling I came to the conclution that the board had suffered the "BMC watchdog death" or the "C2000 bug". The power LED and the BMC "alive" LED lights up and the BMC LED stats flashing after 30 sec or so. But if I try to start the server, the BMC light stops flashing.
There seems to be a lot if broken boards but not much information on how to fix them, so I gave it a go.
As I understand it, the BMC problem was fixed after BMC firmware v00.30.00 and it seems that only freeNAS abuse(d?) the watchdog so that I wears out.
My system hasn't been running freeNAS for a long time and I've had the 00.30.00 firmware a while. So it didn't seems plausible that it had broke my system.
I spoke to the the guys involved in this old thread (thanks @pernils and @James Morrison for helping me with your findings):
www.truenas.com
I read up on the C2000 bug and apperantyly some clock timer, that the CPU delivers, wears out and the 25 Mhz signal gets degraded. The BMC need this signal to start the system.
But there are some luck as well. The signal is routed to the TPM port present on the board. So I hooked up the oscilloscope and found out that the signal was indeed not OK. It should be 3.3V but was only about 0.5V.
There are reports that the official fix from many other manufacturers that repair costumer boards with this problem is simply to power bump the signal back to 3.3V.
On this forum there are some excelent threads describing this exact fix on other boards. Big thanks to all of you :)
On my board the signal was ~0.5V and needed to get to 3.3V. A simple voltage devider with 100ohm and 470ohm, gave me close to 3.3V.
The system started right up and works like a charm. I hope that this can help fixing the Asrocks boards as well.
I did like this:
On the TPM connector, described in the manual on page 21 (https://download.asrock.com/Manual/C2750D4I.pdf) i connected two resistors:
- 100 ohm resistor between PCICLK and +3V
- 470 ohm resistor between PCICLK and GND
I don't know if all boards age the same and if the resistor values can be used on any board. So if you try this, it is at your own risk.
/D
Please keep this thread for the specifics of the C2750D4I board, as used in the FreeNAS Mini. For general C2000 LPC clock degradation discussion, use this other thread instead.
-------
Hi all,
I just wanted to report back my findings after my Asrock c2750d4i board froze one day after about 4 years of flawless service with ESXI (and freeNAS initially).
The unit restarted fine but froze again after a couple of hours and then it wouldn't start. I could access the IPMI interface but that only displayed 3 voltages.
After disconnecting everything and tested the PSU, and a lot of googling I came to the conclution that the board had suffered the "BMC watchdog death" or the "C2000 bug". The power LED and the BMC "alive" LED lights up and the BMC LED stats flashing after 30 sec or so. But if I try to start the server, the BMC light stops flashing.
There seems to be a lot if broken boards but not much information on how to fix them, so I gave it a go.
As I understand it, the BMC problem was fixed after BMC firmware v00.30.00 and it seems that only freeNAS abuse(d?) the watchdog so that I wears out.
My system hasn't been running freeNAS for a long time and I've had the 00.30.00 firmware a while. So it didn't seems plausible that it had broke my system.
I spoke to the the guys involved in this old thread (thanks @pernils and @James Morrison for helping me with your findings):
FreeNAS mini (C2750D4I) repair due watchdogd nand wearout
If you have a FreeNAS mini then you should check and consider to turn the watchdog function off in bios. The mini's motherboard is ASRock C2750D4I and on bios version v2.90 it's by default turned off. As I have encounter 2 failured motherboard it must have been set to on in bios before v2.90...

But there are some luck as well. The signal is routed to the TPM port present on the board. So I hooked up the oscilloscope and found out that the signal was indeed not OK. It should be 3.3V but was only about 0.5V.
There are reports that the official fix from many other manufacturers that repair costumer boards with this problem is simply to power bump the signal back to 3.3V.
On this forum there are some excelent threads describing this exact fix on other boards. Big thanks to all of you :)
On my board the signal was ~0.5V and needed to get to 3.3V. A simple voltage devider with 100ohm and 470ohm, gave me close to 3.3V.
The system started right up and works like a charm. I hope that this can help fixing the Asrocks boards as well.
I did like this:
On the TPM connector, described in the manual on page 21 (https://download.asrock.com/Manual/C2750D4I.pdf) i connected two resistors:
- 100 ohm resistor between PCICLK and +3V
- 470 ohm resistor between PCICLK and GND
I don't know if all boards age the same and if the resistor values can be used on any board. So if you try this, it is at your own risk.
/D
Attachments
Last edited by a moderator: