most I've heard about/used/changed work fine at 3.3V. Power LED is the same as well.
Be careful of the load rating of the LED. That is listed in mA (milliAmps). I wouldn't recommend throwing a 30mA+ LED onto a default HDD LED pin. Most are current limited at 20mA max, if that. Any more could burn a trace or fuse (if its fused at all).