PDF of installation manual for X/Lisa card cage fan.
May be optional for the XLerator 12.5, required or at least strongly recommended for 16 and 18 MHz XLerators.
In general, if you can hold your finger on the middle of the 68000 CPU of the XLerator after it has been running a while, then it has enough cooling. (The threshold of one's discomfort is commonly about 50 degrees C, YMMV.)
Depending on your cooling requirements and the performance of the fan, you have the option of powering it at 12V, 7V, or 5V.
To power it at 12V or 5V, connect the black lead to ground and the red lead to +12 or +5.
To power it at 7V, connect the black lead to +5V and the red lead to +12V (so the difference in potential is 7V).
A few types of 12V fans don't operate reliably at 5V (they don't start spinning when power is applied, although they may keep spinning once started by hand).
(Checked download, looks OK - JDM)
Pics of the sheet metal bracket that holds the fan, top & bottom.
Pic of the assembled XLFan.
The fan is a 60x60x25mm @ 12VDC variety. If conjuring a replacement or making your own in a similar style, selecting one with low noise/SPL/dBA and modest CFM performance is likely sufficient.
The fan is oriented so the airflow is upwards and the wires are opposite the two tabs. Although wire orientation isn't critical, it helps avoid catching the wires in the card edge connectors when the circuit boards are installed.
The corners of the fan are attached to the sheet metal bracket with triangles of double sided foam tape.
The top of the fan has some foam weatherstripping that clamps the fan in the motherboard tray when the CPU board is in place.
Not shown are the clips at the end of the wires.
Thank You!
Pics of the fan in the card cage.
Note the tabs are under the motherboard itself, and are supported by the metal pan under the motherboard.
When the CPU board is installed, the fan is clamped in place via the weatherstripping.