I'm having some trouble installing the CPU into my motherboard. Both appear (on paper) to be compatible. 

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It is when I examine the four notches on either side of the CPU tray, the mirrored notches on the CPU do not line up. I give the processor a gentle nudge one way or the other to see if it will seat. No downward pressure. Being EXTREMELY gentle. My only conclusion is that I'm a newbie and this is a "Duh" moment. Or I have a compatibility issue.