I'm in the process of installing Server 2012R2 on my T20 and after getting the OS setup on my RocketRaid 2720 (due to the fact the T20 only supports 2 SATA 6gbs devices), I enabled Intel Raid in bios and upon reboot, the Intel Raid bios comes up, I can configure the drives plugged into the onboard SATA ports, however the bios for the 2720 no longer comes up.
In the bios I cannot find any settings for changes to allow an addin card's bios to function. So I popped the 2720 in my supermicro server and enabled the on-board Raid and both raid controller bios come up and allow configuration.
I assume all we need is a bios update, so..... lets go Dell!!