MP 1,1-5,1 Cleaning Mac Pro 2010 CPU heatsink and i see this

[yakult121]

Btw, if it's SPI flash failure, MP51.fd is enough to boot (MP51.fd it's the non-serialised/no hardware-IDs generic firmware upgrade image), but not to access iCloud/Messages/FaceTime and the Mac Pro will need a BootROM reconstruction.

I've replaced the SPI chip but there's still no progress, the Mac Pro 2010 is still not booting. Only the CPUA and CPUB OVTMP LED flashes when applying power. I've also tested the PSU and it's working fine with all the necessary voltages. I've got no time to do further investigations now... I'll revisit this perhaps by the yearend.

 

[yakult121]

I've replaced the Logic Board and now it boots. Paid a pretty penny for the replacement Logic Board...