Hi, I have recently purchased a quad-opteron. The MB is a Quartet manufactured by Celestica. The system has 8 GB of RAM (8 dimms, 2 GB per node). The puzzling thing is that only 7.5 GB show up, both during the BIOS startup, and by the OS (SLES 8). Playing around with the dimms, I have found that up to 3 GB everything looks normal. Adding a fourth dimm to the system results in an effective memory of 3.5 GB. Adding extra modules increase the count by 1GB as expected. The dimms are good, and nothing changes by switching dimms or populating the nodes differently. The vendor tells me that this is a known "feature" of the AMD chipset, even for Athlons. I looked up the thing, and found nothing. I am curious to see if this is just a problem with the Opteron chipset, or a more general problem. 0.5 GB seems a lot to disappear... Thank you Alberto Scotti