posted this a while back and got a few answers but now im being told i was given bad advice... mobo: Intel D975Xbx2 proc: Intel Core 2 Duo 2.6 w/ 1066 fsb Now, the board supports memory 533/667/800 MHz. I was told that when running the memory in dual channel mode (equal DIMM's in each channel) that using memory above 533MHz is useless because 533x2=1066 (the fsb speed). So if I put 2 DIMM's in @ 800MHz (1600 combined) that it would be throttled back to 1066 anyway... if this is so, WHY does memory come at 800MHz for my board??? why wouldnt each channel simply run at 800?? At any rate, I bought 2GB ram (2x1GB DIMM's) @ 533MHz. Is the above true for a FACT? Or would I benefit from using the 800MHz ram? If someone has a definitive answer and can explain, I would appreciate it.
There seems to be some confusion here. Memory channels do not add up to a faster memory speed. They add the bit width: each channel is 64-bits wide, and you get 128-bits in dual-channel mode. It does not add each 800MHz or other speed grade to give 1600MHz. This operates like a highway speed limit. If the limit on a 4 lane highway is 75MPH, that limit doesn't go to 300MPH, it stays at 75. Now, for the FSB, there's another thing that needs to be clarified. Core 2, like it's predecessor, the Pentium 4, operates with a quad-pumped FSB. There's a base frequency that the memory and CPU anchor on. It's this number that the CPU speed is determined in conjunction with the multiplier. Here's an example of the math: FSB=(Base Freq) x 4 Assuming that the FSB is 1066 you would do the following: 1066/4=266 (266.5, to be precise, but that's not an option we work with here). The third piece of the puzzle is in regards to DDR/DDR2 speeds. I put a table together here. Unless you're overclocking, then DDR2-533 is exactly what you need. Now, if you wanted to overclock, you'd want to have PC6400/DDR2-800.
sorry guys im a bit slow on this. I have basically the same problem as JJD228 had. I just need to know which two frequency values we are trying to match, to prevent either the CPU or the RAM slowing by the bottleneck effect? I've been looking for this answer for a a while and any help would be appreciated, thanks.
