Yesterday my Mac Pro 5,1 Backplane Logic Board failed on my spare computer. Its only powered on sometimes, I installed some known good ram in the cpu tray, powered up and it shut down. Investigation revealed it would briefly get power then sparks came from these surface mount components just below the second drive bay, and of course it shuts down. I have stripped the machine and ordered another 5,1 backplane. Any idea what these suckers do ? (see attached photo) While I have had the machine I have just had a 680gtx plugged into the 2 power sockets but of course i dont know where the machine has been for the last 8 years !