Hi there managed to resolve this , but you wont like the answer .
Firstly , by scheduler , I mean , that if you do not have VERY specific Firmware level on BIOS / EFI the ESXi5.1 boot up will not succeed . Host will reboot during ESXI start up , more specifically when CPU scheduler is started . This is booting from internal SAS , and with Intel E5-2600 Chipset .
For this config to work we need BIOS level 1.5.1 Build number VVE134TUS . Anything lower of higher than that , will bring back the problem .
To be fair , if you do a deep level search on this Intel chipset , this is listed as the only certified Bios version . Ooops .
Will have to make a note never to flash these systems , as we don't want to repeat this process again .
I have attached the place where ESXi will reboot , for anybody else that might have this problem .
Lost like 3 day in resolving this .
