I'm upgrading an enterprise system to new hardware and have run into a problem fitting a serial connection into the COM2 serial header on the new motherboard.
I've checked the motherboard manuals and the headers seem to be wired identically, but the COM2 header on the new board is physically smaller than the header on the old board. Not by much, there's maybe a millimetre or two's difference between them, but the new board's header is very definitely incompatible with the plug I need to attach to it.
I've noticed that the plug is, however, exactly the size of the 9-pin USB header on the new board and plugs in to that perfectly (with the boards turned off of course - I'm not sure what sort of damage actually sending voltage down those lines would cause).
I should mention that the DB9 port on the back of the board is in use for something else, so I can't just wire the external devices into a female DB9 socket and attach it to that.
The old board is around ten years old, so is this a standard that has changed over time and I can get an adapter for or is this some custom-build enterprise-system weirdness and I should just re-wire the external devices into a smaller plug?
Edit: I've taken a picture of the plug next to the COM ports of the new motherboard. The old motherboard's COM header is bigger, physically it seems identical to the USB headers.
Edit 2: I've taken pictures of both the old and new motherboard's COM headers. Old motherboard's COM2 header (the one that's the same as a USB header):
And the new motherboard's COM headers: