Is DDR3 required for Penryn

[MageXX9]

Since Penryn's FSB is 1333, does it require DDR3 since those are the only ones I see rated at 1333?

 

[DSF]

No. Intel reports an inflated FSB number. They don't give you the clock speed, but the number of transfers/second. Intel's CPUs make four transfers per clock cycle, so the FSB they report is four times as high as the actual FSB clock.

In the same vein, DDR2 is "double-pumped," meaning it makes two transfers per clock cycle. So the number following the DDR2, like DDR2-667, is actually twice as high as the FSB clock.

So to find the matching RAM speed for an Intel processor, cut the FSB they give you in half. For a 1333 Intel chip that means you need DDR2-667 or faster RAM.

 

[Bateluer]

Originally posted by: DSF
No. Intel reports an inflated FSB number. They don't give you the clock speed, but the number of transfers/second. Intel's CPUs make four transfers per clock cycle, so the FSB they report is four times as high as the actual FSB clock.

In the same vein, DDR2 is "double-pumped," meaning it makes two transfers per clock cycle. So the number following the DDR2, like DDR2-667, is actually twice as high as the FSB clock.

So to find the matching RAM speed for an Intel processor, cut the FSB they give you in half. For a 1333 Intel chip that means you need DDR2-667 or faster RAM.

Close, but the P4s and Core 2s have quad pumped busses, so you need to divide by 4 to find the actual clock speed of the FSB. 1333/4 = 333.25 as the actual clock frequency of the FSB.

You can also run the FSB asynchronously from the RAM speeds, so you can run DDR2 533 all the way to the unofficial DDR2-1333, or DDR3 if you have a board that supports it.

 

[DSF]

Originally posted by: Bateluer
Close, but the P4s and Core 2s have quad pumped busses, so you need to divide by 4 to find the actual clock speed of the FSB. 1333/4 = 333.25 as the actual clock frequency of the FSB.

I don't see how that's any different than what I said:

"Intel's CPUs make four transfers per clock cycle, so the FSB they report is four times as high as the actual FSB clock. "

 

[dv8silencer]

Originally posted by: Bateluer

Originally posted by: DSF
No. Intel reports an inflated FSB number. They don't give you the clock speed, but the number of transfers/second. Intel's CPUs make four transfers per clock cycle, so the FSB they report is four times as high as the actual FSB clock.

In the same vein, DDR2 is "double-pumped," meaning it makes two transfers per clock cycle. So the number following the DDR2, like DDR2-667, is actually twice as high as the FSB clock.

So to find the matching RAM speed for an Intel processor, cut the FSB they give you in half. For a 1333 Intel chip that means you need DDR2-667 or faster RAM.

Close, but the P4s and Core 2s have quad pumped busses, so you need to divide by 4 to find the actual clock speed of the FSB. 1333/4 = 333.25 as the actual clock frequency of the FSB.

You can also run the FSB asynchronously from the RAM speeds, so you can run DDR2 533 all the way to the unofficial DDR2-1333, or DDR3 if you have a board that supports it.

DSF just simplified some algebra to get DDR2-XXX value.