Is there any way to tell which Gridseed is not running at maximum speed using Sandor's cpuminer? For example, in this screenshot:
http://i.imgur.com/piH2iDA.pngGridseed #1 is running really slowly, which probably means that I need to either re-seat the heatsink or resolder the resistor. However, how do I determine which one is Gridseed #1? When I unplug the USB cable to a Gridseed, the UI doesn't update to let me know that it's dead, and every Gridseed looks like it's still hashing.
GSD1 is the second on the the list. This means it is the second on your com port list as well. If your com port list starts with COM3, then GSD1 = COM4.
From here you can just open your device manager and start disconnecting miners one by one. If you see COM3 disappearing from your device manager list, then thats your GSD1.

Its highly likely that your miner is faulty. I have one of those as well. Only one core out of 5 is mining. I tried everything to get it working, but i cant tell which component is faulty. Everything looks good for an eye.