1)If you soldered anything to the mainboard before it occured, whatever you are powering from this point is drawing too much power so get rid of it.Also get rid of everything that you can see that might bridge anything near the GPU.
2) X-Clamp replacement
3) eflow GPU and HANA chip
4) If it\'s not the GPU/(H)ANA, it might in rare cases be the CPU and can be fixed by reflowing the CPU.
5) if you flash with xell on JTAG-fixed xbox360 this will appear, flash back to original.
6) also can be caused by a broken trace
This error is caused by a bridged/shorting solder joint under the GPU, (H)ANA-chip or in between.It can also be power related though, for example if you are drawing power from one of the regulators that power the GPU and HANA-chip.Can also be a component that is missing or damaged so look for missing parts near the GPU and the HANA chip. In extremely rare cases it might also be related to the lines that lead from HANA to the CPU.
The chances are however higher that it is the GPU than the HANA chip so you should always first concentrate on the GPU.
Another cause could be due to a broken trace under the board near one of the ram blocks, check the picture in the reference section. Thank you arvydas for reporting this solution!
This error also show up if the CPU ! was taken off the mainboard.