T5500 memory options for 144GB?

You cannot mix ranks/speed/density. QUAD RANK Dimms are NOT supported.

Mixing vendors in a configuration like this is asking for trouble.

There are 6 ram slots on the motherboard and 3 on the 2nd CPU Riser board.  144 Gigs is NOT a supported option.

Maximum Dimm size is 8 gigs meaning 72 Gigs MAX via 9 x 8 gigs.

Any Dimms taller than 30mm must be installed on the motherboard.

http://downloads.dell.com/manuals/common/precision-t5500_setup%20guide_en-us.pdf

Thank you but that is no longer accurate. The manual which I have lists up to 72 GB for 8GB dimms as 16 GB were not readily available as they are now. The manual also lists SR, DR, and MR, which means single, double, and ????. There another post http://en.community.dell.com/support-forums/desktop/f/3514/t/19475314 which talks about the abbreviations which states that MR mean mix ranks and if more than on Quad-Rank DIMM per channel the speed is reduced to 800 Mhz so Quad rank is supported but maybe not recommended. But different DIMM ranks are required?

Multiple memory manufacturers such as crucial list the T5500 working with 16 GB RDIMMs which I trust more than Dells old manual, but I still cannot find real details on how exactly to do it.

I just want to know what will work which may be very different than what Dell tested 4+ years ago.

Thank you.

I disagree.   Ravi is not using Rank terminology correctly.

If you are correct about the rank and density then 288 Gig would be possible aka 32 gig X 9

http://i.dell.com/sites/doccontent/shared-content/data-sheets/en/Documents/Dell-Precision-T5500-SpecSheet.pdf

If you install high-density memory on a motherboard that is not compatible with the module, it will not work at all or only recognize a portion of the memory.

Ranks are sub-units of a memory module which share the same address and data buses and are selected via CS (Chip Select)  in low level addressing. For example, take a memory module with 8 chips on each side, with each chip having 8 bit wide data bus,  then that module would have one rank for each side for a total of 2 ranks, if we define a rank to be 64 bits wide.  That's why High density is not sufficent for some chipsets because the BUS is 128 bits wide. This is also why only 1/2 of each dimm is working when 4 are used. You need RANK 4 ram due to the width of the bus.

Tri Channel Ram Cannot be mixed in ranks.

And crucial supports 72 Gigs  max.

The way they do that is having 3 modules on the 2nd CPU Riser.

9 X 8 = 72   6 on motherboard  3 on the 2nd cpu riser.

http://www.crucial.com/usa/en/compatible-upgrade-for/Dell/precision-workstation-t5500

memory

• Maximum memory: 72GB
• Slots:6 (2 banks of 3)