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Ok if you're for sure getting pulsing on all the power rails, I would try another BIOS just to see if that is the problem. Keep the original, but try a test BIOS from a donor 00165 to see if the machine boots.
I've never swapped a bios before, I know theres stuff to do to get it to work correctly, but do you mean just straight swap for now just to test for boot?
Yes just for testing swap one over. Keep the original in case that is the problem Duke can help you with fixing the ME Region and serial number and all that stuff.
The U6100 I tried was from a 2015 00165 board and this is a 2017.. would that make any difference? I could always try ordering in a new U6100 with a clean ME just to be sure I suppose.
Without the bios, its boosting PM_SLP_S4_L and VCORE in stages by the looks of it. So it boosts after every 2 second pause and changes the voltage up or down each time in a cycle.
VCORE = 0.08v (pause) 0.12v (pause) 0.24v (pause) 0.53v (pause) 1.1v (pause) 1.3v (pause) then does the same in reverse
PM_SLP_S4_L = 0.24v (pause) 0.46v (pause) 0.80v (pause) 1.20v (pause) 2.3v (pause) 2.7v (pause) then reverse
It's almost like it doubles the voltage roughly until it gets to the voltage it wants, then reverses and does it all over again.
Okay, I've gone back through checking the rails... PP3v3_S4 boosts twice the same as every other S4 onwards rail, but after the others boost twice, they drop to 0v. PP3v3_S4 drops to 0.45v and sits there.
The damage was in the U3210 area, so I swapped out U3210 to see if it made a difference.
I now get PP3v3_S4 and it seems like its on because the CPU is getting hot after a min or so and VCORE is a constant 1.8v