You know, I really hate to defend BFL ... but if you look closely, the red solder mask hides the traces pretty well.  But down at the bottom, by the Altera Cyclone IV FPGA, there's a trace going to a clock (just above the 1x PCIe fingers).  That's just the easiest to see I think, there appear to be others, but it's hard to distinguish from the JPEG artifacts.

Still waiting for my BTC paid for Single ...