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brucek

Fsb Vs Ddr3 Speed

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Just to confirm my understanding:DDR3 RAM speed is 3X FSB. So, for an overclocked Q6600 (3.0 GHz) with FSB 333 MHz, 1333 MHz DDR3 is OK- and most likely OK for a 389 MHz FSB as well. Am I correct?Thanks, Bruce.

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DDR3 RAM speed is 4 x FSB. 333MHz FSB x 4 = 1333MHz on the RAM. A 389 FSB x 4 will give you 1556MHz. Can your RAM handle this? If it is rated 1333 then it might but you will probably have to lower your RAM settings (try 9-9-9-27-2T to start) and up the voltage a bit. If your DDR3 is rated at 1600 you're spot on and you should run the RAM at default settings. Again RAM voltage may have to be raised. I run mine at 1333MHz 7-7-7-21-1T 1.9VYour Q6600 at 389FSB x its 9 multiplier gives you 3.5GHz. That 400 FSB is tantalizingly close... 400x9=3.6GHz on the CPU and exactly 1600 on the DDR3 - nice sweet spot!Konrad

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DDR3 RAM speed is 4 x FSB. 333MHz FSB x 4 = 1333MHz on the RAM. A 389 FSB x 4 will give you 1556MHz. Can your RAM handle this? If it is rated 1333 then it might but you will probably have to lower your RAM settings (try 9-9-9-27-2T to start) and up the voltage a bit. If your DDR3 is rated at 1600 you're spot on and you should run the RAM at default settings. Again RAM voltage may have to be raised. I run mine at 1333MHz 7-7-7-21-1T 1.9VYour Q6600 at 389FSB x its 9 multiplier gives you 3.5GHz. That 400 FSB is tantalizingly close... 400x9=3.6GHz on the CPU and exactly 1600 on the DDR3 - nice sweet spot!Konrad
Thanks Konrad,Thanks for correcting my understanding, much appreciated. 1600 DDR3 it is! :)Bruce.

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Ahhh, sorry to contradict, but it's a bit different than that. Intel uses the "Quad Pumped" monicer to describe its Front side buss. For instance, the latest Qs advertise that they run on a 1600Mhz FSB. Others are advertised to run with a 1333 FSB. This is all just marketing jabber. The "quad pumped" description suggests that four data bits can be transferred on each alternating current (A/C) cycle. A single A/C cycle that occurs - over the time period of One Second - is called One Hertz (Hz), after Mr. Heinrich Hertz. A MegaHertz (MHz) is a million alternating current cycles per second. So, if Intel advertises "1600" as their FSB number, they really mean that 1600Mb can be transfered each second via a FSB that is running at 400Mhz (400Mhz x 4bits per cycle = 1600Mb/Hz). The Front Side buss is actually running at 400Mhz. A FSB advertised at "1333" is actually running at 333Mhz.(333Mhz x 4bits per cycle = 1333Mb/Hz). A FSB advertised at "1066" is actually running at 266Mhz.(266Mhz x 4bits per cycle = 1066Mb/Hz). And so on . . . Almost there. Ram can carry 2 data bits per Hz. That's why it's called DDR. It can transfer at Double the Data Rate of the front side buss speed. Ready for some arithametic? Here we go: A FSB advertised at "1333" is actually describing a 333Mhz FSB speed. Any ram that is installed on a system with a FSB running at 333Mhz will be required to transfer data at 2X that FSB speed. That ram MuSt be capable of operating at a DR (data rate) of 666Mb per second (2 bits x 333Mhz). The label the manufactures use to describe ram that is rated to run (or transfer) at this speed is called DDRX-666. The DDR is the primary designation. The DDR"2" or DDR"3" only describe some minor engineering differences . . . . and incompatible pin grid. DDR2 vs DDR3 is simply planned obsolescence. So, these red hot QXXX9999XXX that run on the "1600" FSB - only need DDRX-800 ram - . ThaT's iT. The 1333 FSB systems only need DDR2-666 ram. Generally mobos are defaulted to run ram at this DDR'd speed. Most mobos have bios adjustments that allow users to increase the ram's speed by a multiplier. This is great fun to play with, but will provide only subjective performance increases. It's really hardly worth the trouble from an empirical standpoint . . . but still fun is fun. Ya gotta take where ya an get it. That's also why I like that Q6600. The P35 (X38X/P45/et al) was designed from the get-go to support the final Core2 CPU at a 400Mhz FSB. The little ol Q66 has that sweet 9X multi. The arithmetic works out perfectly. At a 400Mhz FSB, the CPU's 9X multi will drive a GO/Q66 right to it's max stable 3.6Ghz speed. It also will drive any ram installed to that 800 speed designated by DDR2-800 . . . and that stuff is as cheap as dirt these days. DDR2-800 is the stuff needed. Any speed grade above that won't hurt, other than to waste money for expenses - - - other than pizza!

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Ahhh, sorry to contradict, but it's a bit different than that. Intel uses the "Quad Pumped" monicer to describe its Front side buss. For instance, the latest Qs advertise that they run on a 1600Mhz FSB. Others are advertised to run with a 1333 FSB. This is all just marketing jabber. The "quad pumped" description suggests that four data bits can be transferred on each alternating current (A/C) cycle. A single A/C cycle that occurs - over the time period of One Second - is called One Hertz (Hz), after Mr. Heinrich Hertz. A MegaHertz (MHz) is a million alternating current cycles per second. So, if Intel advertises "1600" as their FSB number, they really mean that 1600Mb can be transfered each second via a FSB that is running at 400Mhz (400Mhz x 4bits per cycle = 1600Mb/Hz). The Front Side buss is actually running at 400Mhz. A FSB advertised at "1333" is actually running at 333Mhz.(333Mhz x 4bits per cycle = 1333Mb/Hz). A FSB advertised at "1066" is actually running at 266Mhz.(266Mhz x 4bits per cycle = 1066Mb/Hz). And so on . . . Almost there. Ram can carry 2 data bits per Hz. That's why it's called DDR. It can transfer at Double the Data Rate of the front side buss speed. Ready for some arithametic? Here we go: A FSB advertised at "1333" is actually describing a 333Mhz FSB speed. Any ram that is installed on a system with a FSB running at 333Mhz will be required to transfer data at 2X that FSB speed. That ram MuSt be capable of operating at a DR (data rate) of 666Mb per second (2 bits x 333Mhz). The label the manufactures use to describe ram that is rated to run (or transfer) at this speed is called DDRX-666. The DDR is the primary designation. The DDR"2" or DDR"3" only describe some minor engineering differences . . . . and incompatible pin grid. DDR2 vs DDR3 is simply planned obsolescence. So, these red hot QXXX9999XXX that run on the "1600" FSB - only need DDRX-800 ram - . ThaT's iT. The 1333 FSB systems only need DDR2-666 ram. Generally mobos are defaulted to run ram at this DDR'd speed. Most mobos have bios adjustments that allow users to increase the ram's speed by a multiplier. This is great fun to play with, but will provide only subjective performance increases. It's really hardly worth the trouble from an empirical standpoint . . . but still fun is fun. Ya gotta take where ya an get it. That's also why I like that Q6600. The P35 (X38X/P45/et al) was designed from the get-go to support the final Core2 CPU at a 400Mhz FSB. The little ol Q66 has that sweet 9X multi. The arithmetic works out perfectly. At a 400Mhz FSB, the CPU's 9X multi will drive a GO/Q66 right to it's max stable 3.6Ghz speed. It also will drive any ram installed to that 800 speed designated by DDR2-800 . . . and that stuff is as cheap as dirt these days. DDR2-800 is the stuff needed. Any speed grade above that won't hurt, other than to waste money for expenses - - - other than pizza!
Hi Sam,How does your math apply to DDR3 though? That was in my OP.Thanks for the post, Bruce.

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Sadly, yes. "The DDR"2" or DDR"3" only describe some minor engineering differences . . . . and incompatible pin grid. DDR2 vs DDR3 is simply planned obsolescence."There's no reason to use DDR3 for any socket 775 build. Intel is forcing the issue with their new i7 platform. They changed the memory pin grid so Only DDR3 will physically fit. And so it goes.

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The right DDR3 memory and a properly clocked Q9650 will reward you with a much smoother, clearer, more spectacular FSX experience. A Q6 & DDR2 won't come close. DDR2 is OK but DDR3 is better. A clocked i7 940/965 is even better if you have the money. Don't listen to the guy who likes to buy his steaks at Denny's and his pizza at...7/11? :( -jkEdit: Sam just could have just told you that FSB is quad data rate and DDR(2)(3) is dual data rate and left it at that but he had leave his :( opinion about DDR3 and the i7 and so on...He doesn't fly the sim for the scenery, he couldn't because he doesn't have the parts yet.

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The right DDR3 memory and a properly clocked Q9650 will reward you with a much smoother, clearer, more spectacular FSX experience. A Q6 & DDR2 won't come close. DDR2 is OK but DDR3 is better. A clocked i7 940/965 is even better if you have the money. Don't listen to the guy who likes to buy his steaks at Denny's and his pizza at...7/11? :( -jkEdit: Sam just could have just told you that FSB is quad data rate and DDR(2)(3) is dual data rate and left it at that but he had leave his :( opinion about DDR3 and the i7 and so on...He doesn't fly the sim for the scenery, he couldn't because he doesn't have the parts yet.
Thanks jk :)Bruce.

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