Dual channel 533mhz?? 800fsb (200*4)?? WTF HelP

knowsitall

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Dec 19, 2006
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Ok.. i m confused.. I run everything at stock speeds. I have a pentium D 830.. it has a stock fsb of 800mhz. I also run it with 2 x 512mb 533mhz ram. So does this mean i have dual channel memory? If my pentium d has 800fsb wouldnt that mean it is 200 * 4 to get 800?? and wouldnt my ram be 266.5 * 2 for 533mhz? so since my cpu is 200 and my ram is 266.5 am i bottlenecking?? can someone explain this to me. I ve tried to read other forums about ram issues but cant figure it out.... Help!?

I plan on rebuilding a new rig soon and would like to do some heavy over clocking with a tuniq tower 120 heatsink and really need to understand ram/cpu fsb to choose ram with great headroom an no bottleneck.
 

Mondoman

Splendid
Here's a simplified description of how data is transferred to/from current Intel CPUs (AMDs are conceptually the same):
<RAM> - memory bus - <memory controller> - FSB - <CPU>
The slowest of the 5 components will be the "bottleneck", limiting the overall throughput from end to end, so speeding up other components won't help the overall throughput.

RAM varies in quality and thus in the maximum speed it will run at.

Memory bus speed can be limited by the MB design, but in practice with good MBs, RAM speed hits its limit first.

The more memory controllers, the higher the throughput when they can work at the same time (multi-channel mode). Most modern chipsets now have two memory controllers, doubling throughput when run in dual-channel mode.

FSB speed, like the memory bus speed, can be limited by the MB design.

CPUs vary in quality, and thus in the maximum FSB they will support.

In practice with current C2D CPUs, it's usually the CPU and/or MB limiting the max FSB which acts as the bottleneck, as long as you are running in dual-channel mode.
 

knowsitall

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ok hm that seems interesting but that is not helping me.. what is dual channel mode? what does it do? i have a pentium d 830 3.0 ghz 800fsb. I have 533mhz dd2 ram. shouldnt i drop my ram down to 400hmz so it will be a 1:1 or whatever it is. cuz then my memory bus would be 200 along with the cpu fsb 200*4 given it a 1:1 and no bottle neck rite!?!? anyone!! 8O
 

Mondoman

Splendid
Dual channel mode is when 2 memory controllers are in use at the same time. Having two pipes instead of one means that data can be transferred up to twice as fast.

You say the simplified diagram isn't helping you. Which part(s) need more explanation?

PS - The only way to not have a bottleneck is if *every* link in the chain has the same data transfer rate, which almost never happens in practice. However, some bottlenecks are easier/cheaper to minimize than others.