Hum just wondering why you are worried by mobo temps running at that temp my lappy here runs at 59C and my Sandy Bridge on a Giga H67 board runs at 40 - 46C as a normal usage.
Meant to mention too have just fitted Arctic Freezer 13 Pro's to both my deskies and the temps dropped from average 45C to 26 - 28C. The Arctics were not expensive either.