Power Supply | T400 RPI 2B

[myrcy]

Hello everyone,
        I hope this message finds you well.
I’m reaching out for assistance with flashing a T400 using a Raspberry Pi 2B (at least for now). During the teardown process, I came across the following note:

> A dedicated 3.3V PSU was used to create this guide, but an ATX PSU is also fine.

This seems a bit abrupt, as there was no explanation provided about why a dedicated power supply is necessary, how to set it up, or where to obtain one.

Previously, I successfully Corebooted a ThinkPad X230 with Skulls and did not require an additional power source beyond my micro-USB.

Before I proceed with installing GNU Boot, do I need to purchase a different power supply? If so, does the power supply connect to the machine itself or to the flasher (Raspberry Pi, BeagleBone, etc.)?

Thank you all for your time and assistance—I greatly appreciate any guidance you can offer.

—Best