ASD is definitely not just for Intel macs. 2.6.3 is what i am using on my Quad 2.6 power PC. 2.5.8 was for earlier G5/s. 2.5.8 I am fairly certain is the one you need. I have a copy naturally but no idea of how to get it to you given this forum's rules. Google and burn it and start with it holding down the option key. I think It will tell you cpu 2 is toast but It could also say the temps are out of parameter of heat(needs new thermal paste). I am working the same issue right now with BDaquas support . I need to find out which way the stacked the dual cores inside of the single chips. Your's is an easier case if it turns out that it is shutting down because of heat but is not dead yet. You just need to put your grain sized paste dead center and put the heatsink back on.
apple asd dual boot 2.5.8 cd
2ff7e9595c