Hello everyone. I wanted to share my experience going from barely being able to mod a 360 with a chip to RGH3 chip-less instaboot spectacular.
The best software is JRunner with Extras - this will handle your RGH3 needs. You'll need drivers and to install, you'll need to disable driver signature enforcement. Don't use a shady PC - my desktop has horrible USB ports and kept me on edge if things would work, I swapped over to my laptop and things worked much smoother.
If using a Matrix flasher, change the JRunner mode to MTX mode - I can't believe I missed this and it caused so many issues!!!
If you are on the hunt for a console - slim Trinity is your best bet. If you are out of luck - Jasper and Falcon are fine. Don't bother with consoles that do not have an HDMI port, nor Zephyrs.
What you will need -
Using a chip still has a place in the RGH3 world, I used an Ace v3+ for a Corona 4GB console but the 4GB NAND reader is not the most fun. I tore a trace when I had the tool soldered in and just barely got it fixed and running. I'd highly recommend to steer clear of Corona boards if possible as you could also need a Post-Fix Adapter.
I found that the deeper you go down the rabbit hole, the more hardware you need
so beware which model you have and are attempting. Take your time and read about the process first before you proceed with any of the soldering. I've got 2 consoles fried (skipped resistors and diode) and 3 successes on Corona 4GB (Ace V3+ chip), Trinity (RGH3) and Falcon (RGH3). I have a Zephyr pending completion when the JRunner gets here. Prior to these RGH3 machines I have a CR4XL Trinity that was my first attempt and barely was a success 
A Brief Synopsis
FIrstly - all my knowledge is learned from the internet, I take no credit for revealing any information and in particular order, thanks to sevensins forum, logic sunrise forum, theweekendmodder, and many others that invented these hacks and software. The best software is JRunner with Extras - this will handle your RGH3 needs. You'll need drivers and to install, you'll need to disable driver signature enforcement. Don't use a shady PC - my desktop has horrible USB ports and kept me on edge if things would work, I swapped over to my laptop and things worked much smoother.
If using a Matrix flasher, change the JRunner mode to MTX mode - I can't believe I missed this and it caused so many issues!!!
If you are on the hunt for a console - slim Trinity is your best bet. If you are out of luck - Jasper and Falcon are fine. Don't bother with consoles that do not have an HDMI port, nor Zephyrs.
What you will need -
- NAND Flasher - I use a Matrix NAND Flasher but I have a J-Runner on its way. The choice is yours but TX products usually are better.
- Xbox 360 identification
- google for this, you can easily tell the difference between models.
- DO NOT go for Zephyr systems, you'll need lots of hardware and patience/luck
- Corona 4GB need an SD card reader (I tried 3 before I had success) and an SD Tool to read it
- Soldering Iron, solder equipment - nothing fancy is required
- Single stranded wires work best IMO
- Solder the NAND flasher in
- This will dump the systems NAND Flash
- Solder the RGH3 wires (or your chip)
- YOU NEED THE RESISTOR AND DIODE - do not skip this, they are not optional as some threads might say
- Values will vary, match to your console type
- Dump your NAND (standby power plugged IN, do NOT turn the console on)
- Create ECC
- Write ECC
- UNPLUG the NAND flasher
- Turn the console on and the console should boot into Xell
- You'll get a CPU key, enter that in JRunner or use a network connection to obtain over IP
- Create XeBuild image
- Turn off console, plug in NAND flasher with standby power
- Write the new NAND image
- Unplug and turn the console on. If you get the normal boot sequence, congrats!
- Remove your NAND flasher, you are done! Reassemble.
Using a chip still has a place in the RGH3 world, I used an Ace v3+ for a Corona 4GB console but the 4GB NAND reader is not the most fun. I tore a trace when I had the tool soldered in and just barely got it fixed and running. I'd highly recommend to steer clear of Corona boards if possible as you could also need a Post-Fix Adapter.
I found that the deeper you go down the rabbit hole, the more hardware you need