after reading the TYAN K8WE thread: I have an Opteron running with 2G on an Asus sk8v board since about a year now without any problems. Last week we tried to upgrade to 4gb and run into big trouble. I tried to upgrade from 9.2 to 9.3, but it does not work any better (as I already run a 2.6.11 kernel anyway) But it seems I have two problems in combination: First I learned, that Asus boards with a VIA chipset have some serious hardware problems dealing with >= 4Gb of memory. The Bios offered some switch to map any memory in conflict to regions above 4G, but the newest Bios update misses this option, as it did not work stable. So Q1: does it work in any way with 2.6.12 (i installed now) by setting any iommu=??? Why is addressing above 4gb a problem for a 64-bit cpu, anyway? I bought this 64bit system exactly to get rid of any ugly 4gb limit :-( I got messages like: PCI-DMA: "Out of SW-IOMMU space ..." but I'm not sure about what iommu setting I used for this try. Problem 2 seems to be a serious stability problem when pug in all 4G (4x1G Kingston registered ECC modules). My bios reports spurious strange "SYSTEM FAILURE DUE TO CPU OVERCLOCKING" messages, even if I did not change any settings at all. After several attempts to boot, the system even stays black. Not even any bios comes up. After shortcutting the NV-Ram it works again for some time. With only 2gb it seems to work stable again. Some other discussion threads suggest a weak power supply, but I use some 450W PSU. Is this even too weak to power an Operon + 4gB memory? We also examined the board for any popped capacitor, but they all appear to be fit. I'm willing to send the board to the moon, and get a new one. But following the current discussion about the Tyan board, I'm not sure how to to proceed now. Some suggestions? -- Dieter Stüken, con terra GmbH, Münster stueken@conterra.de http://www.conterra.de/ (0)251-7474-501