There are some options:
1. DVD kit - removes x16 card and leaves you with 12 LFF and 2x8
2. left riser with 2 x8 and 1 x 4
3. left riser with 2 x8 ($10 i paid)
So I'm going to rock the P420/1gb FBWC HP SMARTCACHE $249 raid controller with 4 SSD in read-only cache mode with a fan-out cable and the 12 drives, and run two or three dual 10gbe nic's - the QLE8152 $75-99 cards run at x4 only so you can fit two emulex x8 dual 10gbe nic's in there and 1 QLE8152 for 6 10gbe ports.
If you are good at fabricating it would not be hard to get the the dual x8 riser and fit it in - use some lego's
The only place i've found selling the retrofit kit to put it back to 12LFF proper is a dude in germany who won't ship over here.
Why? Well I've got a 36 drives that were in old DL320s storage servers which are getting old in the tooth.
Why did I choose 5600 series cpu's? Because they suppport SR-IOV and every other server is on 5600 series. You can get non-ES 1.6ghz quad core e5603 cpu's for $70 on ebay. Sure they are slow but they support hardware AES.
Software defined storage (AKA VSA lefthand or nexentastor CE vm ) you can run multiple VSA's per box and other light vm's on the same machine.
One of the nic's i'm selling does 1024 vnic's to linux per port (dual port) that's 2048 nic's - a web hoster's wet dream!
It is truly amazing how much power you can get out of such little $$ these days!
8gb dimms $45 each - 6 yields 48gb
E5603 $70 5600 series cpu with AES-NI and SR-IOV
P420/1gb FBWC $249 (hp smartcache is $249 per SERVER)
Two 10gbe nic's $150 (75 each)
1 Barebones DL180 G6 $$cheap$$ with redundant power ($$CHEAP$$ if you did the sell the old cpu's trick!)
4 SSD to boot and cache the 12 drives (750gb read only cache, 125gb for windows 2012/linux) !! $400
fanout cable $15 for the ssd to P420.
12 RE4 SATA/SAS drives (2/3/4TB) - not cheap but a ton of storage!
Serious power house here!
I priced out a newer DL380p and was well over $10K to do the same config!!