I just installed 24 Gbytes of extra memory to my existing 24G on my SR 2 mobo. When I boot up the machine its only shows 32 Gbytes when showing installed memory. I'm using the same memory modules Patriot MEM 4Gx3|PATRIOT PS312G13ER3K-E RT.
I checked with AIDA64 and the memory modules were identified. I have a dual Intel Xeon X5680 system with no overclocking.