E-66 asked me the following and I thought my reply could be useful in this thread:
You mentioned getting memory that's rated for higher than the stock 1:1 ratio, locking it at that speed, and then overclocking the FSB to match it at the new faster 1:1 ratio. I understand the concept of what you're saying, but I don't understand how the 'locking' part is done. Is it determined by whether or not the motherboard has BIOS settings that allow it to be done, or something else?
Depends on the motherboard you have. Some have a setting dedicated to establishing the ratio between the FSB and the memory, you'll see options like 1:1 2:1 1:2 5:4 3:4, etc... however most modern motherboards, especially ASUS ones, have memory speed settings instead. First you need to determine your motherboard clock speed based on your FSB. Knowing that Intel processors have quad pumped FSBs, your true clock speed is divided by four. So if your CPU is running a 800FSB processor, your clock speed (800 / 4) is 200. DDR memory is double pumped at 1:1, so to get 1:1 with a 200 clock, you need to run your memory at 400MHz. What happens then when you overclock, your memory will follow and still be within the specification it was designed for.
So say you overclock your motherboard's FSB from 200 to 333, which a lot of motherboard easily support due to new processors originating with 1333FSB, you memory if still at 1:1 will now indicate that it's running at 667MHz. If you were to push the FSB to 400MHz, your memory would now be running at 800MHz, as it was originally. However, now instead of running at 1:2, it's running at 1:1. The cpu is now running at double it's speed, the FSB and interconnects are at double speed and the memory is still running at stock speeds. (Memory is the touchiest thing to overclock).