I always found the original Xbox was too large so i put mine inside a x360 E case. First I gutted the x360, cut a hole in the rear for a fan, made cutouts for the rear connectors and added standoffs to mount the motherboard. Next I put the motherboard in and tested it with the original PSU. First problem, the fan wouldn't spin unless I started it by hand, not ideal. It was a 12v fan, just like the original. After some testing I found that the Xbox will output a constant12v on the positive line but will vary the negative line for speed control, and the start up voltage difference was too low for my fan. So my options were to get a new fan or some other solution. I chose some other solution. I added a delay ON relay that switches the fan negative from earth to the motherboard negative terminal. So when power is applied the fan gets the full 12v and a second later the relay switches and gets the motherboard negative fan control signal. Now onto the next problem, the power supply. There is no room in the 360 case for the original power supply and I wanted to use the 360 supply. The original PSU output directly to the motherboard 12v, 5v and 3.3v. The 360 PSU outputs 5v standby and 12v when on. An ON signal must be sent to the PSU for it to output 12v To convert the voltage I used 2 suitably sized DC to DC converters to take the 12v from the 360 PSU and convert it to the required 5v standby, 3.3v PSOK, 12v On and 5v ON lines. I also created a circuit that controls the power on sequence. Such as, the front panel power button is pressed, the 360 psu receives a power on signal and turns on, supplying 12v to the DC-DC converters, one of these converters converts the 12v into the required 5v standby voltage plus the 3.3v PSOK signal. after a short delay to allow power to stabilise, a picaxe micro processor sends the motherboard a power on signal to simulate the front panel button being pressed, the motherboard then sends this request to the other DC-DC converer which switches on and supplies 5v and 12v to the Xbox. Top left is the power on sequence controller, bottom right is the DC-DC converters. Top right by the fan is the delay ON relay circuit. Also I wired two controller ports to the back panel and wired the other two ports to the USB ports on the front panel. And here it is all together. I use a wireless controller with the receiver in the back panel.