FSB & Memory Speeds

[Orbs]

Hi Everyone,

I am planning on buying the following:
- http://www.newegg.com/Product/...x?Item=N82E16819115034
- http://www.newegg.com/Product/...k=N82E16813131219%253a
- http://www.newegg.com/Product/...x?Item=N82E16820208343

The CPU supports a 1,333 MHz FSB and the Mobo supports both a 1,333 MHz FSB and a 1,200 MHz memory clock. The RAM is spec'ed at 1,200 MHz.

I'm not sure if a 1,333 MHz FSB and a 1,200 MHz memory clock line up though. It seems like a 1.11 multiplier would be required (though I'm not sure if I'm calculating this correctly). I don't really want to overclock these components as I like warrantees .

Will these components work together? If not, what should I change (ie: what component should I swap out to have the smallest performance impact, but allow me to operate the components within spec)?

Thanks!
Jared

 

[DSF]

Time for the old "What does FSB really mean?" discussion.

Intel processors don't report the clock frequency of the frontside bus (FSB), they report the number of transfers/second, which is 4x higher. (In other words, the CPU you chose makes 4 transfers per clock cycle on a 333MHz FSB, for a total of 1333.)

Similarly, RAM modules don't report the actual FSB either. They also report the number of transfers/second, but in this case, the number is only 2x higher because DDR/DDR2/DDR3 make two transfers/clock cycle. DDR2-1200 isn't running on a FSB of 1200, it's actually only rated for a FSB of 1200/2 = 600MHz. Still, this is considerably higher than any stock desktop processor requires today.

So, to recap, the true FSB speed of your CPU is only 333MHz. This means that to match the FSB speed of the processor, you need DDR2-667. DDR2-800 is in many cases just as cheap. DDR2-667 and DDR2-800 are both fully compatible with your motherboard.

If you're planning to overclock the processor, you may want that higher-performance DDR2, but only if you're planning to push the FSB past 400MHz. If you're not planning on overclocking, I have to wonder why you're spending $1000 on that chip. (Frankly I have to wonder why you'd spend that much money on a CPU at all, when chips of nearly equal performance will be out for 1/3rd of the price within months.)

 

[Orbs]

Thanks, DSF. Your response makes sense to me, however I recall seeing improved performance in benchmarks that compare DDR2-667 with DDR2-800 (though the improvements were marginal). If DDR2-667 matches CPU's with 333MHz FSBs (or lower as I believe 1,066 transfers was standard before 1,333 transfers became standard), how does going to faster memory improve performance (without increasing the CPU's FSB)? Or perhaps my recollection is incorrect.

I'm buying the CPU from a friend so I won't be paying $1,000. The other components I'm buying will be retail.