After you get yourself a new Raspberry Pi, you might have being through lots with it like playing around to catch a glimpse of the awesome gadget but anyway, there is usually this noticeable but depending on your patience unnoticeable rainbow colored splash screen that come and go just while you boot the device. There’s a good chance you’ve also seen the more curious version of that, the same rainbow pattern, shrunk down and flashing in the corner of your screen. Okay let’s seriously think it straight.
The rainbow screen which appears on all boots are tests o the GPU but this boot screen splash might be very fast and never catch your attention which you look away from the screen since its quickly fast. because it flashes by pretty quickly. However, if your screen freezes at this rainbow screen, then you likely have one of two problems.
The device might suggest that the Kernel .IMG file isn’t booting as it should and so you might need to check out your SD card but fixing it means trying some new images or try messing around the config page. Also, the meaning of the sudden pause might be your low power supply which might not be strong enough for the system to function well and so you might need to increase your voltage here.
Speaking of power supply problems, if you see the rainbow colored cube in the corner of your screen, that means your power supply is incorrect. If it’s a rainbow, it means your power supply is under-voltage. If it’s red, it’s over-temperature. Your Raspberry Pi might still continue to work with either of these issues, but you should get the correct power supply as soon as possible.
source: Engadget