My 2011 iMac suddenly stopped working about 6 weeks ago. I spent 4 weekends in a row testing, replacing parts, returning parts that did not resolve the problem. Finally, my last hope was to buy a used logic board to see if that was the problem since I had absolutely no startup. Well, this logic board worked and brought back to life my 10 year old iMac and it works great again. Thanks so much for sending a quality product and for a reasonable price. Shipping was also faster than anticipated.