First off retail kernels will not detect 3.5" HDD's so make sure you're RGH'd or JTag'd. Now let's get to it. As we all know the 360 is designed only to be used with a 2.5" laptop sized hard drive and as such only supports 5v, which means that we are unable to connect full sized 3.5" hard drives to the motherboard without some type of external power supply... This tutorial will show you how to solder a 12v/5v SATA power connector and standard SATA data cable straight to the motherboard and allow you to use any SATA hdd of your choice (2.5" and 3.5"). 1. Disassemble your Xbox 360 all the way down to the motherboard. (i won't cover this, there is tuts on this site and all over the internet on how to do this) 2. Solder your SATA data cable as shown below: (make sure you do not forget to wire the ground wires otherwise your SATA cable will be subject to interference and may not detect your HDD) 3. Run your SATA data cable along the bottom of your motherboard as shown below: 4. Put your motherboard back inside the metal cage, and let your SATA data cable feed out in front of the fans as shown below: 5. Solder your SATA power cable as shown below: 6. Drill a hole in your case and install a grommet as shown below (1" size is ideal for feeding the SATA data/power cables through) 7. Reassemble your Xbox 360 with the SATA data/power cables coming out of the top of the case as shown below: Thanks for reading and i hope you learnt something new. Any questions? Feel free to quote this post and i will answer them ASAP. Disclaimer: It is your responsibility if anything goes wrong during this process.