R6T3
R6T3 is the label of a resistor on the mainboard of the Xbox 360. It supplies the necessary voltage for the Xenon CPU to burn the so-called e-fuses. Burned e-fuses prevent older firmwares (currently any older rev. than 4552) from running on your Xbox 360, thus eliminating the possibility to downgrade to an earlier version of the kernel. The Resistor itself is located in the field T-6. It is a 10k Ohm (10,000 Ohm) SMT resistor (Case 0402) functioning as part of a current limiting circuit.
The removal of R6T3 will cause an E80 system error if the NXE update is installed. Replacing the resistor with the original or with another 10K Ohm resistor usually fixes the error state. Given the difficulty in surface mounting a resistor as small as R6T3, simply holding a 10K Ohm in place while the 360 is powering up after giving a E80 will typically allow normal operation from then on. Care must be taken not to bridge the gap without a resistor in place as this may cause system damage.
