OK, I got my GTX460 working...
The voltage regulators seemed to be OK so I moved to the GPU. I decided to try Louis Rossmann's advice and burned the chip at 120 C for 10 min. I do not have an preheater so I used a coffee warmer as the hot plate. That preheated the GPU to about 60C (measured at the package top) from the bottom then I used my hot air station to heat it from above for 10 min and monitored the package temperature with the Fluke meter. Then let it cool down naturally. Put it in the computer and -Bang!- it worked ! Pulled out one more time, applied thermal paste, installed the heatsink, put the card back and measured the current consumption.
With full GPU utilization the two +12V rails supplied 8.5A+2.6A, a total of about 11A, 133W or something.
Also took a peek with my Flir E4 thermal imager and found the major heat generation offender was actually the onboard power supplies, not the GPU, as can be seen in the attached pictures. The left picture is the card in idle mode (just Windows desktop), the right picture is the card under 99% GPU stress using a test utility. The power regulators are on the other side of the board under the fan cover and on full steam they heat the right side of the board right through to 80 C
while the GPU was almost 20 C cooler.
The card is not going to be used for games anymore, just for my Altium backup station, as such I do not expect the GPU to be stressed much, so hopefully the card will last for the next little while.