there should be no reason you can't replace it electrically, the only complication should be mounting holes and the placement of the network cable
the biggest problems I spotted with that thing is that is its like double the cost of a full motherboard/ram/cpu combo
I created an enclosure with x9scm/e3-1220/8gb ram for like 1/3 the price; this way my ipmi port is already in the right place, and I just stuck freenas on it, which allows email alerts or whatever I might find useful
there is an official bracket that goes with it...but they are VERY hard to find, and almost the same cost as the cb3 board itself
thank you.
In the end I decided to buy the CB3 board, it costs 160 USD new.
I have very little free space in the rack to add a separate box and I cannot install a full motherboard in this JBOD as there is very little space in it. I like CB3.
For anyone looking to do the conversion:
I found the official Supermicro CB2 to CB3 conversion mounting bracket for like 5 USD new, part number: MCP-120-84702-0N
The IPMI LAN extension cable is also needed, part number: CBL-NTWK-0587 (16 USD new). The bracket for the extension cable: MCP-120-84706-0N (4 USD). The cable to connect the backplanes to the CB3 board: CBL-CDAT-0601 (3 USD). You need total two, for the front and rear backplanes. I already had one because the rear backplane was connected to the CB2 board already, but not the front backplane for some reason.
This is how it looks:
Issues so far:
1. It seems the CB3 board only detects one PSU for some reason. When I log in to the IPMI interface, only one PSU is listed as active there, the other one is not detected. The cable from the power distributor is connected to the CB3 board and it detects one of the PSUs, just not both of them. However, both PSUs are working fine.
Anybody has any idea why?
2. one of the LED on the rear backplane is red. I checked the manual and it indicates fan failure. The fans are working fine, maybe it just indicates fan failure because no fans are connected to the backplane? They are connected to the CB3 board so that I have speed control. According to the user manual I can short pins on the backplane to disable the fan failure indicator but I'm out of jumpers for this backplane.
But overall I'm very satisfied with the result, fans are a lot quieter now plus we have manual fan RPM control via the IPMI command line.
Everything is working as it should, including front panel buttons and front led indicators such as power on, network activity, error, etc.
All temperature sensors inside the jbod are correctly reported too.