title: Why would a slower clock rate 20 v 40 MHz be better at driving an LED matrix
body: <p>I'm looking into creating a custom shield for driving an LED matrix, looking at clock speeds which can drive the matrix based off this thread(<a href="http://forums.adafruit.com/viewtopic.php?f=47&amp;t=26130&amp;start=0" rel="nofollow">http://forums.adafruit.com/viewtopic.php?f=47&amp;t=26130&amp;start=0</a>) it seems that >50MHz is unable to drive the matrix. How is this possible? I thought a fast clock rate would be better at driving an LED matrix...</p>
  
  <p>I'm looking at using at ATMega328-pu which has a clock speed of 20MHz.</p>