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Help me understand CPU/Memory/FSB

Last response: in Systems
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December 29, 2007 12:54:09 AM

I'm in the planning stages of building a new system. I began first by researching all the recent technologies, etc in order to make sure everything is compatible and what not. I found this site http://www.directron.com/fsbguide.html explaining how to choose components. I am a bit confused with that guide, specifically with "Generally you want to keep the system clock of your memory matching with the root clock of your memory or one step above. So the system clock on a 800MHz FSB P4 is 200 (quad pumped) so that matches DDR2 400 (essentially 200 unimproved) or is good with 1 step up DDR2 533MHz (essentially 266 unimproved). Note however that if you only had a 800MHz FSB processor then DDR2 667 really probably isn't going to help much. Once you pass the 1 step above mark on the memory you have diminishing returns unless you can get to double (DDR2 800MHz)." So from my understanding, you should try to keep the CPU, memory, and FSB at a 1:1 ratio. But reading the above, it says going past the 1:1 ratio will have diminishing returns unless you reach a 2:1 ratio, what is the benefit of a 2:1 ratio?

Now for more specific questions regarding what I learned from the above guide. I'd like to use the Intel core 2 extreme CPU rated at 1333FSB. Would I divide the FSB by 4 (quad pumped) to get 333Mhz and find a motherboard that has 400FSB along with DDR2 memory at 800 (400FSB) to reach a balanced 1:1 ratio?

I'm assuming my understanding is a bit flawed so any advice is welcome. Thanks in advance.
a b B Homebuilt system
December 29, 2007 1:25:45 AM

The 1:1 balance would be DDR2 667(333 double pumped). By getting the DDR2 800 ram, you could OC the processor FSB to 400 to match the ram. Combined with the multiplier of the CPU, your processor would run at "9 x 400 FSB - 3.6 Ghz". This assumes the processor was the 3ghz model to begin with. This also assumes a quality MB from ASUS, Gigabyte, etc...

Additionally, the DDR2 800 would allow a 1:1 FSB match for a newer 1600 FSB 45nm Penryn processor upgrade, or an overclock on the 1333 FSB model..
December 29, 2007 3:27:21 AM

For motherboard selection would I match the CPU FSB rating after quad pumping? So an Intel core 2 extreme rated at 1333FSB would need a motherboard that supports 1333FSB or 333FSB?
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a b B Homebuilt system
December 29, 2007 4:05:04 AM

needhelp1 said:
For motherboard selection would I match the CPU FSB rating after quad pumping? So an Intel core 2 extreme rated at 1333FSB would need a motherboard that supports 1333FSB or 333FSB?

1333. You might also look at some of the new boards that support 1600 FSB to allow for more upgrade room. The x38 boards are one such example. http://www.newegg.com/Product/ProductList.aspx?Submit=E...
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