The glitch chip is the heart of the Reset Glitch Hack (RGH), currently the predominant method of modding an Xbox 360 to play homebrews and backup.
The X360ACE v3 is a reliable and versatile glitch chip that can be used in various RGH methods (EXT_CLK, RGH 1.2, RGH 2) covering all models of Xbox 360, EXCEPT for Winchester boards (later E models) which are incompatible with all methods of RGH. To identify which board revision you have and which RGH method is right for you, I recommend the following pages on the ConsoleMods wiki:
The X360ACE allows you to tweak the glitch timing to ensure reliability on whatever console you install it on, and will also ship with enough wire for installation.
NOTE: The Reset Glitch Hack is a challenging mod that requires delicate surface mount soldering. I recommend beginners practice on something else before attempting it.
NOTE: The Reset Glitch Hack also requires a NAND flasher (not included) to rewrite the 360’s firmware and (optionally) tweak the X360ACE’s timing.
NOTE: Later Xbox 360 E models (Winchester boards) are incompatible with the Reset Glitch Hack. Make sure to check which version of 360 you have before purchasing.