DL380 G5 - CPU upgrade E5335 to E5472 No Video

Hi,

I have a pair of Xeon E5472 CPUs I wanted to use to upgrade one of my DL380 G5 servers but after doing so I get no video, all fans run at 100% and iLO thinks the old CPUs are still in there while the insight front panel reports no faults. Putting the old E5335s in results in the server coming up as normal. With the CPUs in, the diagnostic lights on the inside read as follows and do not change:

Front ------------------------------ Back
OFF ON OFF OFF OFF OFF OFF OFF

I'm currently guessing I need to update the BIOS firmware to enable support for these CPUs but wanted to throw this out in case anyone knew of any other reasons why the system doesn't seem to be taking the upgrade?

For reference, this has system board 436526-001 which does support these CPUs according to my research. It has 32Gb RAM (8x4Gb all identical) also. Anyone else with a VMware lab experienced this at all?