32-bit is 8 bits per colour channel (24-bit) plus an 8-bit alpha (transparency) channel, not 10-and-a-bit bits per channel. The alpha isn't (normally) sent to the display device, it's used to render overlapping elements at the display generation level (video card). Good LCDs can easily render the full colour depth with headroom to spare. Higher-end graphics monitors are often 12-bit (the extra range is used for calibration/display accuracy, not necessarily for greater depth).