Question Why would DELL loop the pin 5 (RESET) & pin 9 (RESERVED) on the JFP1?

sean.mohrhoff

Prominent
Feb 9, 2018
3
0
510
Greetings! I plan to re-purpose a DELL Dimension 2400 case which I read can house a micro ATX (mATX) motherboard. Looking at the wires coming from the front end, I notice most of the wires line up properly, following the colored wires from the front to the pins they connect. The only thing that's off is there is a short length of wire running from pin 5, RESET SWITCH, to pin 9, RESERVED. Instead of typical wires from a DIY case where wires are either single connections or paired connections, the DELL case has all the wires in a single connector that resembles a USB 2.0 header, the difference being pin 10 is typically missing from the JFP1 (which is still true here) and pin 9 is missing from the USB 2.0 header (also still true here). This won't be an issue as DIY mobos have open headers for JFP1, so I'm not worried about the shape, just the way 5 & 7 is shorted.

So again, why would the original configuration involve shorting 5 (RESET SWITCH) to 9 (RESERVED) and leaving 7 (also RESET SWITCH) bare? I'd like to have an answer and recommendations before I get the new mobo in.

Thank you in advance.
Sean M.
 

sean.mohrhoff

Prominent
Feb 9, 2018
3
0
510
Apparently its for the "case is open" which prevents it from booting. I learned this when I had it open, unplugging bits and then turning it back on to see what sort of error messages I would get. None, as it refuses to power up when the case is open.

Now I'm wondering if I should cut the wire or see if it still behaves the same (if the loop is proprietary to the mobo or not).

Thanks for responding!