I am running a Mac Pro 1,1 that was firmware upgraded to 2,1 and runs the latest version of El Capitan (10.11.6) thanks to Piker Alpha's modified boot.efi. The computer has an ATI Radeon HD 5750 video card with a modified ROM that makes it appear in the OS as a 5770. Boot screen is showing. Everything works fine except I cannot get it to restart.
When I tell it to "restart" all I get is a black screen and the PSU won't switch-off. Looks like it cannot complete the command. I looked inside the case and always when that happens I get two diagnostic LEDs flashing: the CPU-A and CPU-B. Rare flashes. Computer unresponsive. Then I just kill it by holding the on/off switch until the shutdown. These LEDs never go on when the computer is being used. Just at an attempt to restart.
All of the other power-related topics seem to be working perfectly. Sleep is available and stable, same with remaining switched on - no sudden unwanted shutdowns. While trying to find a solution to the issue I've already:
1) checked the system with the Apple Hardware Test - no errors were found;
2) exchanged the 5750 for the stock GeForce 7300 GT Mac Edition that came with the computer - still no restart but the diagnostic LEDs started to flash in a different manner: this time they flash in fast series of short flashes of differing length (amount of flashes) - once it is 4 quick flashes, "pause" then 9 quick flashes, "pause", then 11 quick flashes", "pause", then 5 quick flashes, etc.;
3) I've reset the NVRAM (option+command+P+R at startup) - no change;
4) I've pressed the SMC button button on the motherboard - no change;
Any ideas?
When I tell it to "restart" all I get is a black screen and the PSU won't switch-off. Looks like it cannot complete the command. I looked inside the case and always when that happens I get two diagnostic LEDs flashing: the CPU-A and CPU-B. Rare flashes. Computer unresponsive. Then I just kill it by holding the on/off switch until the shutdown. These LEDs never go on when the computer is being used. Just at an attempt to restart.
All of the other power-related topics seem to be working perfectly. Sleep is available and stable, same with remaining switched on - no sudden unwanted shutdowns. While trying to find a solution to the issue I've already:
1) checked the system with the Apple Hardware Test - no errors were found;
2) exchanged the 5750 for the stock GeForce 7300 GT Mac Edition that came with the computer - still no restart but the diagnostic LEDs started to flash in a different manner: this time they flash in fast series of short flashes of differing length (amount of flashes) - once it is 4 quick flashes, "pause" then 9 quick flashes, "pause", then 11 quick flashes", "pause", then 5 quick flashes, etc.;
3) I've reset the NVRAM (option+command+P+R at startup) - no change;
4) I've pressed the SMC button button on the motherboard - no change;
Any ideas?