This kit is designed to mount a high airflow quiet fan in the place of the stock Dreamcast fan. It is specifically built for the Noctua NF-A4x10 5V fan.
This mod shines in systems with GDROM emulators like the USB-GDROM and the GDEMU. It makes those systems nearly silent. It may not do much to systems with the original disk drive still installed as the disk drive is louder than the cooling fan.
Please note this kit is not compatible with early revision Dreamcast consoles know as VA0, these systems are fairly rare in all regions except Japan. The easiest way to determine if you have this model is to open the system, if you have a silver or grey fan attached to a metal heatsink it is a VA0.
And the Dreamcast Noctua Fan Cable, which custom built conversion cable that plugs into the original fan connector and converts the signal so that the new fan functions properly (built in 10K resistor).