I have an Intel D875PBZ, which has been flawless. I recently tried to upgrade the memory from 1GB to 3GB by adding what I was told by a salesperson as the correct 2 X 1GB PC3200 DDR400 modules to match/compliment the existing 2 X 512MB PC3200 DDR400 configuration. The Intel documentation seems quite specific about the requirement that memory modules exhibit serial presence detect (SPD) in order to achieve the best performance.
I searched all over trying to find modules that list SPD in their specifications. I couldn't find anything. An online retail salesperson sold me two OCZ 4001024V3 modules saying that they would work fine. I stuck with OCZ since everyone seemed to recommend not crossing brands. However, the motherboard immediately detected these modules as being non-SPD compliant and notified me that it was reverting all memory modules to the lowest possible performance for the sake of stability. The system seemed a little less responsive so I returned the memory.
I noticed from OCZ's web site that the timings on the recently purchased modules (OCZ 4001024V3) are 3-4-4-8, whereas the original memory in the machine (OCZ 4001024ELDC-K) is marked 2-2-3-6. Aside from the SPD issue it seems like a mismatch to begin with. The original modules are wrapped in a copper shield/heat sink. I haven't seen these anywhere.
Searching the OCZ site the closest match to the original I can find is OCZ EL DDR PC-3200 Dual Channel *EOL, which has timings of 2-3-2-6, which is not exactly the same but certainly closer.
Does any of this make sense to anyone? Can someone at Intel or this board tell me exactly what modules I need to compliment existing memory and upgrade my machine using PC3200 DDR400 1024MB modules THAT UTILIZE SPD and where I can obtain them? Your help is greatly appreciated.
Incidentally, I found this nice SPD utility called SPDTool (http://www.techpowerup.com/spdtool/). It provides a lot of detailed info about your onboard memory configuration and the ability (Expert Only Mode!) to write back various operational settings.