Aurora Red Tower Warning Light?

I have an Alienware Aurora desktop configured to purple colors for the normal tower lights.  Yesterday I noticed that one of those lights (on the left side, where the panel opens) has turned red.  (The other side is still purple, as is the little alien guy on the front.)  I'm assuming this indicates a hardware issue of some kind, but a reboot and update to the Alienware tools do not seem to indicate any warnings as to what the issue might be...

Within a couple of minutes of starting a game, I noticed some unusual lag, but there have been no BSODs or other hiccups otherwise.  I was thinking either overheating, memory, or graphics card, but I'm not sure...  Is there a tool to see what the light is all about?