Recently bought my first raspberry pi 2 B and I'm wondering what PSU I should use, I have 2 adapters and I wonder which one would be best:

either 5.35v 2A or 5.1v 2.1A


3 Answers 3


They both provide 10.7W, however I would use 5.1V 2.1A because

  • it's closer to 5V for USB peripnerals
  • it's closer to 3.3V rPi is using, and the DC to DC switching converter to create 3.3V from higher voltage is more efficient and with less ripple if the higher voltage is closer to 3.3V
  • They both provide 10.7W. No! The fuse will only allow 2A, so one will provide 10.7W and the other 10.2W. But since the internal circuit is expecting 5V, it won't matter much. Big chance the over-voltage is burned instead of effectively used.
    – Mast
    Sep 1, 2015 at 19:20

It probably will not make any difference which one you use. The voltage at the Pi is determined by the PSU voltage and the voltage drop in the microUSB cable you use.

You will need to measure the voltage at the Pi. Claims on labels may not meet reality.

The Pi2 will draw as much current as it needs. Both the PSUs say they can supply the 2 amps which is all that the Pi2's polyfuse will pass.


You should use 5.1v adaptor. As far as i know, pi will work safely with 5v +- 0.25v. I have run once pi with 4.8v fine, but i wouldn't push upper limits.

That said, follow the advice and measure voltages. Tags usually are just specs.

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