maxing out memory on 1850 and 2850

Memory Population Rules for 2850/1850:

The Lindenhurst chipset only supports 4 Ranks per channel where a 3 DIMM per channel design requires six to not have any population restrictions. The figures below show how the four ranks are used which does not allow dual ranked DIMMs to be used in slots DIMM3_A and DIMM3_B and does not allow any DIMMs to be used in slots DIMM3_A and DIMM3_B if dual rank DIMMs are used in DIMM2_A and DIMM2_B. With these restrictions, the PowerEdge 2850 is fully populated with four dual ranked DIMMs, six single ranked DIMMs, or four single ranked DIMMs plus two dual ranked DIMMs.

• Always populate DIMMs in matched pairs. i.e. DIMM1_A and DIMM1_B, DIMM2_A and DIMM2_B, and DIMM3_A and DIMM3_B must match
• Always start populating memory from DIMM1_B and DIMM1_A
• Always populate dual ranked parts first
• If four dual ranked parts are used then DIMM3_A and DIMM3_B are not usable
• Dual ranked parts are never supported in DIMM3_A and DIMM3_B

• Unless you can find single-rank (1R) 4GB DIMM's (which I don't think they make), the only way to get to 16GB is with four 4GB DIMM's.

, or four single ranked DIMMs plus two dual ranked DIMMs.

Didn't think this was possible.  I thought that if bank 1 or 2 contained dual ranked that bank 3 had to be empty.  Also I thought the matched pairs is only for optimal performance, not an actual requirement?

I think i'd be ok though since I can move the 2GB modules into two of the other machines moving them to 8GB each.  Just don't want the dimms going to waste.