Originally posted by: slobber
Hey,
The VNF4/ULTRA manual says:
"Due to CPU specifications limitation, two DDR400 memory
modules inserted into DIMM1/3, three DDR400 into DIMM1/2/3,
or four DDR400 into DIMM1/2/3/4 is not recommended."
So you can't load up the DIMMS?
I assume that if I get 2x512 I should put them is sloft 1 and 2....then I can never add memory? The manual is *VERY* lacking.
I also downloaded the memory compatibilty PDF file. It is also vague about the details. FOr example it claims to support 512MB PC3200 from mushkin, but gives NO part numbers.
thanks guys,
OK, here is the deal on the 4 memory slots with this board (and this applies to ALL Nforce4 boards). The Nforce spec does NOT allow for running 4 DIMMS at 400MHZ in dual channel at a 1T command rate for most memory modules (I am told that DIMMS with chips on only 1 side of the PCB are supported, and those with chips on both sides are not, but I have not been able to confirm this myself, not having any single sided DIMMS).
Any Nforce4 board which has all 4 slots filled with 400MHZ RAM in Dual Channel mode will set the RAM speed to 333MHZ as if the ram were PC2700 instead of PC3200, and will impose a 2T command rate. Most of the boards (including the Chaintech) will simply allow you to set the speed of the RAM back to 400MHZ in BIOS, BUT the RAM cannot (to my knowledge) be set back to a 1T command rate. This incurs somewhat of a performance hit, since RAM at 1T will be able to function much faster than RAM at 2T, BUT the performance increase from the extra RAM may outwieigh this (This was the case for me, I get better benchmarks with my Kingston HyperX at 4 x 512MB in 2T than 2 X 512MB 1T).
The reason that they do not recommend using 3 DIMMS is that it cannot run the third DIMM in dual channel (since there is only 1 stick of RAM in that channel). I have heard conflicting stories from people as to whether there is really a negative impact from this or not, and again, the performance benefit from an extra stick of RAM may outweigh the loss from having 1 stick in single channel). Putting 2 DIMMS into slots 1 and 3 is simply not recommended because you will not be able to run them in dual channel mode (since each will be on it's own channel).
So basically, the reason they do not recommend these configurations is because there is a potential performance loss, BUT the RAM and the board WILL work in these configurations. It is up to you whether you want to be brave and try them out. Myself, I bought my second 2 RAM sticks before finding out that the board did not fully support 4 DIMMS. Given the chance, I would have sold my old 2 sticks, and just bought 2 1GB sticks of RAM, but it was too late for me.
Also, do not necessarily put too much credence in thier supported RAM list. This is merely a list of all of the DIMMS that they have gotten around to extensively testing with this board. I have heard from tons of people who successfully use this board with value and no-name-brand RAM without a problem. Some of them mixing multiple no-name makers and/or RAM sizes without any problems. So do not sweat that, and just be aware that the 4 DIMMS issue is for ALL Nforce4 boards.