The Asian CAT team, together with Jimmy May (The Aspiring geek himself), the MS PFE SAP team and HP have published a very interesting blog about DL980 configuration:
If you plan to run on that machine, I highly recommend you read up on the great information in the blog.
Whenever you play around with an HP server, I generally recommend you download and skim through the QuickSpec. It gives you the details of how the machine is laid out – the PCI card speeds and placement come in quite handy when you configure the machine with FusionIO.
Another good resource for large machine tuning is to take a look at the full disclosure reports on TPC-E runs