USB connectors at the side were blue while the third one at the back was yellow. Initially I thought this was simply a matter of aesthetics, but after a while I noticed that some devices behaved differently depending upon which colour port I plugged my device into.
I did a little bit of research on the internet and it seems that this is not just an arbitrary colour scheme. The blue USB ports implement the new USB 3.0 standard. Although this new standard offers the promise of dramatic increases in speed, there are not many devices in the market yet which use this standard. While USB 3.0 should be mostly backward compatible with USB 2.0, the yellow USB 2.0 port is supplied just in case there are any incompatibilities. In addition, the yellow connectors also have a neat feature in that they allow you charge up you USB devices even when the laptop is turned off (see here for details).
Many people seem confused by the different port colour and not everyone sees exactly the same behavior depending upon their BIOS configuration (e.g. this query in the Lenovo forum). My own personal observations are as follows (your own mileage may vary):
- If I have a USB mouse or keyboard plugged into the blue USB port when I turn on the laptop it will fail the power on self test. However, if I plug a USB mouse or keyboard into these ports after the laptop has booted they will work fine.
- If I have a bootable USB key the laptop will only boot from it if it is plugged into the yellow USB port.
- My mobile phone can be charged from any of the USB ports, but it seems to charge up much quicker when I plug it into the yellow port as compared to when I plug it into a blue port (this seems to conflict with some information on the web which implies that USB 3.0 has higher power capabilities)