Core temperatures 10 degrees higher in one CPU than another, is this cause for concern?

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http://serverfault.com – We have a new Dell server with a pair of 6-core Xeon 2620s for a total of 12 cores. Using Speedfan/HW Monitor, I notice that the cores associated with one of the CPUs run about 10 degrees hotter under load than the other CPU (mid 60s centigrade vs mid-50s). At idle, the numbers are a little closer, but the hottest core idles at around 45 and the coolest idles at about 35 or so, but the two groups of traces are not as distinct as under load, where clearly there are two groups of temperatures. It's been a while since I built and ran my own servers, but if this was a home computer I'd built my (HowTos)