I'm building a new system with a Core 2 Duo E6600 (Dual 2.4 Ghz). I'll be using a 975X chipset motherboard, either the Intel D975XBX2 (Bad Axe 2) or the Asus P5W DH Deluxe. Both of these boards are rated exactly the same: 1066Mhz FSB and 800/667/533 Mhz RAM.
My questions: Will there be any harm in using 1066 Mhz RAM with these boards? Will I be overclocking anytime I'm running the RAM at 1066?
I don't know if I'll overclock or not, and I want to keep my options open, IF it's safe to run the DDR2 1066 RAM in these boards.
1) For a standard C2D FSB data rate 1066MHz CPU, one or two pairs of DDR2-533 (running in dual channel mode) are enough to saturate the FSB's sustained bandwidth. However, running RAM at DDR2-800 or faster speed on such a system will give small additional performance improvements. See this article: http://www.madshrimps.be/?action=getarticle&number=1&ar...
2) You didn't specify what component(s) you will be overclocking. CPU? RAM? Motherboard components such as the chipset north bridge?
I think he might be over-analyzing your question. No, running 1066 RAM will not overclock your computer. The RAM is guaranteed to be able to run up to 1066, however, the motherboard will still control the speed of the RAM. So, if you put 1066 RAM into a computer with an 800 MHz FSB, it will clock the RAM down to match the FSB by default. Keep in mind that the RAM speed is in single channel. If you use 2 sticks, the RAM will be in dual channel, capable of running at an effective speed of 2132 MHz, far faster than you need. If you are planning on doing some overclocking in the future, 800MHz RAM is plenty fast enough for most people. That allows, when in dual channel, a FSB speed up to 1600 MHz, much higher than the standard 800 or 1066 FSB of todays CPUs. If you don't want to overclock, 667 RAM is fast enough for all the 1066 FSB CPUs today. Yes, it is safe to use 1066 RAM, but you probably won't need to.
I should mention that you don't need 1066 RAM, unless you are only using a single stick. If you are using 1 stick of RAM then you should use 1066 RAM. 2 sticks doubles not only the capacity but also the speed, so with 2 sticks you get twice the capacity, but it also allows you to use slower RAM, which is cheaper. It's the reason people use 2 sticks instead of 1.