Okay, I'm not sure where all you guys are pulling your answers from.
DDR = Double Data Rate. So, take my CPU for example. It has a 333mhz fsb. But, I believe that's only it's maximum. When I first booted it, it was set to 166mhz, with an 11x multiplier. So, 166mhz x 11 = 1826mhz. That is the equivalent of a 2.5ghz Intel chip. It's the AMD 2500+.
But, I have a problem. I bought DDR 400. What that means, is that it actually runs at 200mhz, but due to the way it's designed, acts like 400mhz. Of course my fsb is only 166mhz, thus my RAM defaulted to DDR 333.
Now I have upped the fsb on the CPU to 175mhz. So, since I retain my 11x multiplier, I now have a 1925mhz CPU, an increase of about 100mhz. Also, I instructed the memory to maintain a 6/6 ratio with the fsb, IE, 1 to 1. So, since the ram is DDR, I now have 350mhz Ram.
So, in short, the actual fsb is much different from what is called out on the specs. It depends on your motherboard settings. I get a good performance boost by increasing my fsb by only 9mhz. My CPU is now 5.4% faster, and my RAM is now 5.1% faster.
In the morning when the outside temp is cool, I only have a 2.5C increase in temp upping the fsb by 9mhz. As soon as I get some AS5, I plan on bringing it all the way up to a 200mhz fsb x11 for 2.2ghz or 3200+, thus saving $106 (Newegg) on buying the larger chip, and bringing my RAM to DDR 400.
You can run your ram at speeds other than 1/1. It's just that you get the best performance at 1/1. So, I could easily set my ram to 6/5. With a fsb at 166, 6/5ths of 166=200. 200x2=400mhz (DDR again).
bingo. the memory will clock to whatever speed it is set at. since the guy had a 333mhz bus his ram will run at 333mhz