[coreboot] Power supply and X220

[Felix Held]

Hi!

> You should only power your BBB with an external 5V power supplier,  > and connect its usb peripheral port to your controlling computer. > 
I have never used any ATX power supplier for this, just the > 
configuration I just described is enough.
For a x220 the 3,3V regulator on the BBB likely doesn't supply enough 
current, since the Thinkpads usually don't have a diode in the power 
supply line of the SPI flash and so you power part of the board when you 
apply the 3,3V to the flash chip. Using an ATX power supply for the 3,3V 
can be quite dangerous though; if you connect it to the wrong pins, you 
can easily fry your board, since it can supply quite some current.

Regards
Felix