There are plenty of issues with the XBOX that cause the RROD, in all it's forms. After working with my lab's wiring shop to try and fix a 1stgen XBOX with 3 light RROD, we tried the following...
1. New PS unit.
2. Removed Xclamps and refastened with machine screws and new heatsink compound.
3. Reflowed board twice using our own method (as it was not recommended by our guys to heat both sides of the board, as there are several resistor packs on the underside that may become dislodged ).
And
4. Replaced several of the 2200uf capacitors on the logic board... that more than anything else, got the Xbox to respond better... check those caps !