Question case fan conroller 5V cable to motherboard?

[MikeL78]

have the View 51 case. Inside the back panel on the reverse of motherboard (MSI B550) is a fan controller panel. I have been updating my water (removed AIO, installed open-loop, etc) and fan cooling and detaching many cables in the process. On this controller panel there is a connection labled 5V m/b-in DO GND and I do now not seem to have any cable with the specific end to attach to this connection; somehow lost it. Please inform me of the cable that I need to connect this fan hub connector to motherboard.

 

[Paperdoc]

I cannot find in the manual for that case any details of the fan hub you cite. It may or may not be for fan MOTORS - it may be for the LIGHTS in fans, OR for both motors and fans.

But here's my suspicion. The case is fitted with some system (probably based on this board) for control the the ARGB LIGHTS in fan frames. On p. 12 of the case manual it shows the layout of the front panel (top right edge) buttons and indicators. The bottom button of that group is the Reset button. BUT that page indicates that, like many other systems, it has re-purposed the Reset button to be the manual selector button for setting lighting display patterns. The last option among its choices is to hold the button in for at least three seconds to tell the built-in lighting controller to turn over control to ARGB signals being supplied from a mobo ARGB header. For that, there are illustrations to show how to connect an included cable from some board port to a mobo header. NOTE that the labels they show on the mobo headers are: +5V D (blank) G. Those are the standard pins of an ARGB header, with the third position missing its pin so it has no label. In the BOARD label you cite, the "O" may simply mean
"missing pin". "D" means the Digital Control Line.

So, IF you had lighted fans working before, then you must have had the required cable installed earlier from that board port to a mobo ARGB header, but note the MSI usually calls such a header the JRAINBOW header; your mobo has two of these near the front edge at top and bottom. On the other hand, if you never had lighted fans working, you may never have used this system or never have made that connection, so the cable supplied with your case may be stashed someplace with spare parts.