Memory, FSB, DDR2 and speeds...

[Ghost]

My head is going to explode. I swear.

Looking to buy the Gigabyte GA-P35 board. It lists the FSB as either, 1333 or 1066. OK, simple enough. The FSB is 1333 or 1066. But wait. I'm told that these FSB's are "Quad" pumped, and really only running at 333 or 266. Am I correct so far?

That doesn't really mesh with my brain. Kind of feels like I'm told that a car can go 200 mph, but it really only goes 50.

In my ignorance, I thought it was best to buy memory that matched the 1333 or 1066 FSB speed. As DDR3 is too expensive, I was going to run the FSB at 1066 and get DDR2 1067 rated RAM.

But no, in another thread, I'm told that my 1067 RAM I was considering only really runs at 533. Hmmm, I see a trend forming. Speeds that are listed as X really aren't X. Just a little confusing don't you think!?!

OK, so in that other thread, I was told that because my TRUE FSB speed is either 333 or 266, that getting 1067 RAM that is really running at 533 is not necessary. As the 533 RAM would actually slow down to 333 or 266, a waste. Am I correct so far?

It was recommended that I go with DDR2-800 which is really running at 400 Mhz. So it still has to slow down to the 333 or 266, right?

Why not go with DDR2-667 which is really 333 Mhz which would match my FSB if I set it at 1333, right? It wouldn't have to slow down at all, and I would probably save some cash, correct?

Please, illuminate the fog of ignorance that I'm in!

Hellllpppppp

P.S. I'm assuming it makes more sense to run the FSB at 1333, as long as the ram I buy runs equal to, or greater than 333Mhz, right?

 

[sutahz]

Yup FSB is only 266 or 333.
Ahhh, but it FEELS like your going 200MPH.
You dont have to buy ram that matches the FSB of the cpu, as you've shown yourself.
1066 ram is running at 533MHz (DDR=Double Data Rate) so 533x2=1066, right?
You can run your ram faster then the FSB, but it won't give you a performance bost like the advertisements try to tell you.
You could go to w/ DDR2-667 if your not overclocking. Even if you are overclocking, some 667 can be taken up to 1000 im sure.

You actually understand everything, you just dont like what you know.

 

[Brutus04]

Doh! ...well said.

 

[Mondoman]

I'll just add that what you're getting confused about is that sometimes people are talking about clock rates and sometimes they are talking about data rates. A 333MHz FSB *clock* speed results in a 1333MHz *data* rate, because the FSB transfers 4 chunks of data in 1 clock cycle. Double Data Rate 2 (DDR2) RAM transfers 2 chunks of data in 1 memory bus clock cycle. To confuse things even more, most current MBs can run RAM in "dual channel" mode, which transfers data to/from 2 DIMMs at once in parallel, or 4 chunks of data in 1 memory bus clock cycle. DDR2-xxxx numbers refer to the *data* rate from a *single* memory DIMM, so a DIMM running at DDR2-667 is running at a 333MHz memory bus clock speed, but a 667MHz memory bus data rate.

 

[Ghost]

Originally posted by: Mondoman
I'll just add that what you're getting confused about is that sometimes people are talking about clock rates and sometimes they are talking about data rates. A 333MHz FSB *clock* speed results in a 1333MHz *data* rate, because the FSB transfers 4 chunks of data in 1 clock cycle. Double Data Rate 2 (DDR2) RAM transfers 2 chunks of data in 1 memory bus clock cycle. To confuse things even more, most current MBs can run RAM in "dual channel" mode, which transfers data to/from 2 DIMMs at once in parallel, or 4 chunks of data in 1 memory bus clock cycle. DDR2-xxxx numbers refer to the *data* rate from a *single* memory DIMM, so a DIMM running at DDR2-667 is running at a 333MHz memory bus clock speed, but a 667MHz memory bus data rate.

But even thought the *data* rate for both FSB and Memory lists as say 1333, that doesn't matter in the sense that you have to match the *clock* rate, which is 333.

That was the piece that was confusing to me.

You see *data* rate numbers all over. But the key is matching the *clock* rate.