[email protected] wrote: > 4. For 32GB configuration (2 x 16GB sticks), installing to the > closest orange slot of each CPU would not boot, it booted when I > installed the sticks to the second closest orange slot of each CPU.
If you install memory modules as far *away* from CPU/chipset as possible then you create more margin in DRAM signal integrity, which can make the system work more reliably even if memory initialization is not perfect. The reason is that signals reflect everywhere on the memory bus. When the chipset drives signals and modules are installed nearby, the signal will reflect back at the last slot and possibly interfere with either the controller's request or the DRAM's response. The same happens when the DRAM drives signals, in response to requests. They go out from the DRAM and both left to the chipset and right towards those unpopulated memory slots, and then reflects there, possibly interfering with what the DRAM sent or with the next request from the controller. Mainboard memory busses, especially with many slots, go right up to the limit of physics, and yes there is supposed to be a little bit of margin and there are some workarounds available, but all of that is the responsibility of the memory initialization, and it's very easy to not get everything 100% right. Then stuff doesn't always work. With this in mind, the safest bet should be, to populate a single DRAM module per channel, as far away from the chipset as possible. //Peter _______________________________________________ coreboot mailing list -- [email protected] To unsubscribe send an email to [email protected]
