DDR3 800 faster than DDR3 1333?

[germs]

I came across this article earlier, as I was looking for more information on DDR3:

http://www.nehalemnews.com/2008/05/e...hy-fsb-is.html

The chart:



Since 666 FSB is currently impossible, wouldn't it be better to buy 4 gigs of DDR3 800 mhz than 4 gigs for DDR3 1333 mhz for a slightly overclocked Q9450 (333 FSB 8x multiplier, will hit at least 400 mhz)?

It would seem that the 12.6 GB/s would be superior to the 10.7 GB/s. I wasn't sure if those theoretical numbers would be very close to the real values, so I did what little testing I could in Everest ultimate edition:

DDR2 333 mhz dual channeled (expected values calculated the same way the chart does):

4874 MB/s, or 4.76 GB/s. Expected value: 5.33 GB/s.
Percent difference: 12%

DDR 333 (single channel): 2451 MB/s, or 2.39 GB/s. Expected value: 2.66 GB/s.
Percent difference: 11%

Based on that data (quite possibly erroneous, as the testing methods were obviously not the best), you could expect DDR3 800, when dual channeled, to out perform DDR3 1333, which is currently impossible to dual channel? In addition, DDR3 800 would offer lower latencies, but I'm not taking that into consideration here.

So, is 4 1 gig sticks of DDR3 800 currently superior to 4 1 gig sticks of DDR3 1333 on an overclocked system? Hard to believe, because I can't find any on newegg.

 

[sneekypeet]

Why does a bus of 666 matter...thats why there are memory dividers....I can get my ram to boot over 1200MHz with a divider on a 400FBS!

So then a P35 that can boot 500FSB would allow even higher ram clocks.

In an OC'd situation I'd put my $$$ on the 1333Ram

 

[germs]

I knew I was missing something. Thanks.

I'm going to assume memory dividers can also act as multipliers then? Still in the process of absorbing all those overclock stickies.

Such as, 400 FSB with 3/1 memory divider=1200 mhz memory FSB? In which case you'd need more voltage, correct?

 

[sneekypeet]

voltage may be a non issue...if the CPU is in spec and the ram esentially isnt overclocked at 1200MHz ...no extra voltage other than stock would be needed....except maybe to the NB?

And yes they (dividers) have the ability to increase past the FSB speeds as well as lower it on the 775 rigs at least!

 

[germs]

Ah, thanks for clearing that up for me. Helps to get some real aplications mixed in with the stickies.

 

[Mussels]

on intel chipsets (at least P35 and above) the memory divider seems to ONLY work as a 'multiplier' - the lowest it goes is 1:1 (400MHz FSB means DDR2 800) but at 400MHz FSB, my mobo has an option for 1200Mhz ram, so there you go.