I used a different approach. I got a small relay for 5v/5v and plugged the command voltage to the PSU1 .
It has a very small delay (less than a second) and it powers up my second PSU by closing the Power_Good and a earth wire (black).
Then the PSU2 powers up the cdrom, the cdrw , the fan controller , the pump relay , etc etc etc... all the non essencial stuff .
PSU1 still powers the mobo , the hard drives and the 9700 and has a bit more to spare if necessary .
Works great , no need for tampering, no voided warranty and i can uninstall the thing in 10s.
beware of bad quality pics

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Cables ... and the
relay(the small one, the other one is for the pump and a PWM with a 3A TIP32).