Dell T7500 dual cpu configuration

I have an issue with my Dell T7500. I recently purchased a riser board and new CPUs to upgrade. Once installed with half the 32Gb of memory for each CPU, when booted the machine fails to reach Post and the fans run at 100%. I have tested each of the new CPUs (Xeon X5690) on the primary board and they both work so faulty CPUs is not the issue. Each memory stick (Hynix 8GB PC3 1006DDR) is identical and it was originally installed and running on the primary board. There were some posts online about providing extra physical support for the dual CPU riser which I have tried without success. Can someone please provide me with a solution? Many thanks.