E6750 memory question

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E6750 memory question

Post by R3N3G4D3 » Mon Sep 03, 2007 9:06 am

I was looking at E6750 processor and now becoming more confused. At first, the fact that it has 1333 MHz bus speed lead me to believe that it uses DDR3 memory (Since that's a DDR3 frequency). However, one of the benchmarks used the processor with 800 MHz of dual-channel Corsair memory instead. But it makes no sense for this processor to only support DDR2 since that defeats the purpose of 1333 MHz bus speed, since memory is still the bottleneck. Does that mean that this processor can use both (DDR2 and DDR3)? I thought that each processor only supports 1 type of memory architecture, I've also been looking through Intel datasheets and couldn't find a clear answer either.

What type of memory does E6750 actually use? And if it is compataible with both, would I see any performance increase over 1066 MHz processors if I use it with DDR2? I really don't want to get DDR3 now since it costs about 5 times as much as DDR2.

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Re: E6750 memory question

Post by DMB2000uk » Mon Sep 03, 2007 10:32 am

Aha, let me enlighten you (not sure why I wrote 'aha' then :rolleyes: )

The FSB of Intel processors is Quad pumped, meaning it has a base clock setting, and then it is accessed 4 times for every tick of its clock. This means that the actual BUS speed is 266Mhz for 1066Mhz FSB and 333MHz for 1333MHz FSB processors.

Therefore for it to be able to operate in sync with memory it uses dividers to scale up or down this base FSB frequency to match the memory. Again DDR (any type) is accessed more than once every clock, DDR stands for double data rate, so it is accessed 2 times for every tick of its clock. So this means that DDR running at 800Mhz would have a base clock of 400Mhz.

For a processor to be able to use the different types of memory it has to have a compatible chipset and memory controller that supports the memory. So it is in fact motherboard limited to what memory it can use (as both the memory controller and chipset are on the board).

So to answer your question, all core 2 duo's can use either DDR2 or DDR3, it just depends what motherboard you use them with. With swapping to DDR3 in real world tangible performance, i.e. speed differences you will be able to notice, there is no point for going for it over DDR2. So stick with some nice DDR2. ^_^

The 1333MHz FSB processors will outperform the 1066MHz FSB processors by a small percentage (see some reviews here on LR for actual figures).

Hopefully you will have gathered that due to the way memory is rated, it actually runs faster base clock for base clock than the FSB, so it is not as much of a bottleneck as you might think. LR did an article a while back about how much performance you would gain from using faster memory, and for each jump (i think they did 533, 667 and 800) there was hardly any difference, with games in particular (I presume you are a gamer :P) there was an increase of about 2 fps between the memories tested (look it up for other benchmarks and results).

So 800MHz or even 1066Mhz DDR2 will do you fine. (Go for the higher if you plan on overclocking).

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