Sign in with
Sign up | Sign in
Your question

Memory Speed vs. Mobo/CPU FSB?

Last response: in Memory
Share
May 14, 2008 3:08:34 AM

Hi, I just have a really simple question.. I'm not a tech guy at all, but I know that FSB for motherboard, cpu and memory card should be approximately same in order to maximize PC performance. I chose CPU E8400 which is 1333MHz and Mobo GIGABYTE GA-P35-DS3L, which is 1333/1066MHz. Now I look at the memory card, and many say 2G of DDR2-800 PC2-6400 is good enough. I don't understand why. How can I see if the memory speed is compatible with mobo and CPU? It may sound silly for many of you, but could you explain how DDR2-800 is good enough for 1333MHz mobo and CPU?
June 6, 2008 1:53:22 PM

Hey, I know exactly how you feel, I just posted the same question earlier today, I'll give you my understanding of the issue.

The CPU's real FSB is 333, its 'quad pumped' (333x4=1333)or something, there are technical reasons behind it but I find it easier to just think of it as Intel lying in their marketing.

The Ram is DDR2-800. Again the value has been doubled (*Double Data Ram so times the rate by 2) so it is really 400 (by dividing by 2).

There you go, the ram is actually faster then your CPU. In fact DDR2-667 is actually rated at 333 (667 / 2), which would match up perfectly with your CPU's FSB giving you a 1:1 ratio and maximum performance.

I don't know if i believe this train of thought, but that is my understanding of it. Surely ram at 1333 must give some performance gains over ram at 667?
a b } Memory
a b à CPUs
June 6, 2008 3:29:26 PM

The front side buss transmits data 4 times per clock cycle.
Memory is times 2

So 1066 is actually 266 x 4, and therefore DDR2 533 RAM is a 1:1 match
In your case, 1333 is 333 x 4, and therefore DDR2 667 is the 1:1

Buying faster RAM can get you more throughput, and allows for CPU overclocking without breaking any "rules" for memory speeds. This is important because memory is very significantly less tolerant to overclocking than (current Intel) CPU's. Applying the math above, you can up your front side buss to 400 (x 4 = 1600) and use DDR2 800 RAM... Resulting in a tidy overclock for your Processor, *and* happy RAM.


Quote:
The CPU's real FSB is 333, its 'quad pumped' (333x4=1333)or something, there are technical reasons behind it but I find it easier to just think of it as Intel lying in their marketing.


Well... Since it's easier than trying to learn and understand the facts, then yah... Better to blame Intel for your ignorance. After all, conspiracy theories and "lies" are a whole lot easier than learning to THINK.
!