Hi, Last week I submitted a request for help concerning a kernel panic during a RAM upgrade. First, thanks to everyone who had suggestions. Second, I solved the problem and thought that I would just give a short summary. The machine is an 8-way 64-bit Tyan AMD Opteron machine, originally with 8 GB of RAM. My wish was to upgrade to 16 GB since the machine is used for some very memory-intensive numerical simulations. So, my IT folks ordered 8 additional memory modules (since they would prefer that researchers such as myself not place orders), but upon popping in 4 of the new modules, I received a kernel panic on re-boot. Returning to the original memory configuration did not solve the problem, and I was left with a dead machine. The motherboard has 4 CPUs, each with a 4-slot memory bank. Then there is an expansion board with an additional 4 CPUs and 4 additional memory banks. The problem in the end was simple. The new modules are PC2700, while the originals are PC3200 (thanks IT). Mixing them in a single bank did not work. Also, the BIOS apparently made some modifications upon the first re-boot that hosed its original configuration. To solve the problem, I've reset the BIOS to operate all the modules at 166 MHz instead of 200 MHz. Then I installed 4 of the new modules in each of two CPU banks on the expansion board, and increased the remaining two banks to 2 GB each with older PC3200 modules. Oh, and set the BIOS to read the memory-type automatically (it is a Phoenix BIOS). No kernel or other OS modifications were necessary. I determined early on that the problem was hardware-based by attempting a boot with a Kubuntu 64-bit live CD, but got a similar kernel panic. The trick was to not mix the module types for a single CPU. The system now has 16GB RAM, and while the RAM is running a bit slower, we are after increased memory, not really increased speed (it's pretty fast as is). This is not an optimal solution or memory configuration, and I plan to eventually replace the PC2700 modules with 3200s, and funds permit. Oh, one last thing. One person pointed out that memtest86 does not work with ECC RAM, but I was able to run it from the Kubuntu CD, though not from the Fedora rescue disc. Any ideas? Peter -- Dr. Peter D. Roopnarine, Assoc. Curator Department of Invertebrate Zoology & Geology California Academy of Sciences 875 Howard St. San Francisco CA 94103 Phone: (415) 321-8271 FAX: (415) 321-8615 http://zeus.calacademy.org/roopnarine/peter.htm "Description must be nonlinear, and prediction must be linear." Alan M. Turing
