Do you have a special air shroud for the 111LT-360CB chassis that can be used with the X8DTL-iF motherboard and Intel Xeon E5620? The IOH and the second CPU get very hot.
The 111LT-360B chassis is only suitable for low voltage CPUs (i.e. L5604). The maximum power consumption of the low voltage CPUs is 35W. The E5620 processor has a TDP of 80 W, so the E5620 has a lot more heat and is the source of your heat problem.