Newb question about memory

[Idks]

I was helping my girlfriend build a rig and I picked out a DS3.
When I came time to buy the processor I wanted, I saw the e6550 was released today.
Originally, I was going to get the 6450. No big deal, until I saw the jump in the Front Side Bus.

I missed something in translation when reading the specs.
The 6420 has a 1066 FSB.

Four lane access to the north bridge gives me a 266MHz system clock.
DDR gives me 226 * 2 or 533MHz memory. Which is what I bought.

What would the system clock be for a 6550?
Could it really be 333MHz system clock?

Unless the memory controller is untied from the system clock, is there any reason to buy anything not X2 the system clock?

If not, then DDR2-667 would be my best bet right? I don't understand how the board could support speeds above this without the memory controller being independent of the system clock. This is where I need help, and my username tells the story-I'm new at this. Any help would be appreciated, I thank you much to any that reply.

 

[nobly]

E6550 65 nm 4MB L2 2.33 GHz 1333 MHz
So the E6550 has a FSB speed of 1333Mhz. So you need to get memory that is rated for 667Mhz at least. The system's clock is then 333Mhz.
The chipset you get (on the motherboard) should support FSB speeds of 1333Mhz.

In comparison, the E6420 is
E6420 65 nm 4MB L2 2.13 GHz 1066 MHz
So for this processor, you need memory rated at 533Mhz and a chipset rated at 1066Mhz. The system clock is 266Mhz.

 

[Idks]

Thank you for the reply.

I have a quick question though, why would anyone use memory speeds higher than 2X the system clock? Overclock the FSB?

 

[nobly]

Thank you for the reply.

I have a quick question though, why would anyone use memory speeds higher than 2X the system clock? Overclock the FSB?

Yes, for overclocking the FSB and hence, overclocking the CPU. Its common to get DDR2-800Mhz. I would recommend getting DDR2-800Mhz if its the same price. I have a E6420 with DDR2-800Mhz in case I ever upgrade my processor to the 1333Mhz FSB ones. And if I wanted to overclock. The 800Mhz modules will downclock to 667Mhz if you don't do anything.

Pretty much all the confusion with memory speeds, real FSB speed, and the touted FSB speed is marketing's fault.

 

[Idks]

Outstanding, and I know this may sound rehearsed, but I mean it-that was informative and it helped clear things up quite a bit. I was hoping to overclock her rig and improve memory performance. Information about the different buses in a PC is hard to find-what they do and how they interrelate-and being a 1st time overclocker, the importance of the IO bus and the use of dividers. Also, after reading about the extensive use and practice of CPU-Z (here as well as THG's use of it in benchmarks), I see that I'll have to include that among my often used software tools. Thanks to each of you, you have been helpfull.