I've had the opportunity to turn on my 12 core for the first time today (bought it a few weeks ago), and the first thing I've done is run the apple hardware test. It states an error sadly, which I've decoded already. The code includes 4SNS (system sensors), it also includes "T" for Temperature and "M" for Memory or memory riser board, according to this site: http://www.cnet.com/news/how-to-invoke-and-interpret-the-apple-hardware-tests/ I'm wondering - what exactly are these memory temperature sensors and where do I find them? Are they hard to replace? I still have one year warranty on the Mac. Are these sensors in the Mac, or in the RAM? According to the seller the RAM was new. The only thing I've changed in the Mac so far was the graphic card. I don't think it has to do with this, however. Thanks a lot!