Chris S posted <[EMAIL PROTECTED]>, excerpted below, on Sun, 12 Jun 2005 10:54:26 +1000:
> On a side note, when using 4 x sticks of ram per CPU on your mainboard do > you still get DUAL DDR? > Or is it reduced back to single DDR when using more than 2 sticks? According to their documentation and BIOS settings, dual-channel memory access is per CPU-paired sticks. Thus, two matched sticks in slots 0,1, or slots 2,3, will yield the /ability/ to do dual-channel 64-bit access, if the BIOS is set up to do so, by interleaving the addresses on the individual sticks of the pairs. According to the docs, it should /continue/ to work with all four slots full as well, since the first pair and the second pair work independently of each other. In fact, from the documentation, it should be perfectly happy with unmatched low-pair-vs-high-pair, as well. Two 512MB sticks in the low pair, two 1GB sticks in the high pair, should /still/ do dual-channel 64-bit DDR access -- according to the mobo docs. Also note that with the dual CPU on the board, the BIOS is set up to actually allow effectively QUAD channel memory access, 128-bit, interleaving across BOTH sets of low pairs, and/or BOTH sets of high pairs, if all four sticks across the two CPUs are properly matched. However, with Linux and BIOS NUMA support as well, one must choose between 128-bit inter-node interleaving and NUMA. If you enable inter-node interleaving, you by definition disable NUMA since the memory addresses are interleaved across both CPUs. Disabling 128-bit quad-channel access, setting same-node interleaving, dual-channel 64-bit access only, still allows the dual-channel access per node, while ALSO allowing NUMA addressing, with each CPU (single or now dual-core) getting "local" access to its memory to run its threads, in preference to cross-HYPERLINK access to the memory associated with the other CPU and memory controller. -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman in http://www.linuxdevcenter.com/pub/a/linux/2004/12/22/rms_interview.html -- [email protected] mailing list
