I don't know if Supermicro and DELL is using the same components, but I had issues with a DELL M420 using the vanilla ISO from Vmware, DELL support advised us to try their own custom ISO and it worked well. The DELL ISO can be found here: http://www.dell.com/support/drivers/se/sv/sebsdt1/DriverDetails/Product/poweredge-m420?driverId=5GYKN&osCode=XI51&fileId=3102095257
Can be worth a try.