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What fsb speed do I have

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September 17, 2010 1:01:51 AM

I want to know what my fsb speed is. If it is given on the CPU-Z, please tell me where on the program I can find it. I have another question. I was told by a guy in a different forum that the RAM speed will not run any faster than the fsb speed and that the fsb speed is listed as only half of what the RAM speed is listed as, so 400 Mhz fsb is the same speed as a 800 Mhz RAM stick. Is this guy correct?

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a b à CPUs
September 17, 2010 2:06:00 AM

What processor do you have?
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a c 131 à CPUs
September 17, 2010 2:32:28 PM

You see where it says "bus speed" under the CPU tab? That is your FSB.

I was told by a guy in a different forum that the RAM speed will not run any faster than the fsb speed and that the fsb speed is listed as only half of what the RAM speed is listed as, so 400 Mhz fsb is the same speed as a 800 Mhz RAM stick. Is this guy correct?
No. The ram speed is a multiple of the FSB speed. The ram speed listed for DDR/DDR2/DDR3 under the memory tab ("dram frequency") is half the effective speed. The effective speed is always what is advertised. So DDR2 800MHz runs at 400MHz. But it transfers data on both the rising and falling edge of the clock so it is effectively twice as fast as a theoretical SD RAM 400MHz, which would only transfer data on the rising (or falling, I am unsure) edge.

So for example you have a FSB of 200MHz to make things easy. You have DDR2 800MHz. The ram multiplier will be default 2x. The ram speed will be 400MHz but will be twice that fast effectively.
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September 18, 2010 6:03:55 PM

@ cjl - I have an AMD X2 dual core 5600+ 2.8 MHz CPU

@ Enzo Matrix - thx for the info. You might be saying what the guy that I was told about this was saying, so I may have just gotten my info. incorrect, but anyhow I understand most of it better now. The only thing that I am not sure of what you mean is the rising and falling edge of the clock. Will you please give me a little detail of what you mean by this? Do you mean RAM clock speed or CPU clock speed?
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a c 131 à CPUs
September 18, 2010 6:59:15 PM

dragonfly522 said:
Will you please give me a little detail of what you mean by this? Do you mean RAM clock speed or CPU clock speed?

I'm talking about with the ram. Here is the clock:
__ __ __
| |__| |__| |__
^rising edge

__ __ __
| |__| |__| |__
^falling edge

The ram would be edge triggered, so in SD ram, data would be transferred when the clock hits the rising edge. in DDR /2 /3 this is triggered on both the rising edge and the falling edge, effectively being twice as fast.
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a b à CPUs
September 19, 2010 1:45:26 AM

dragonfly522 said:
@ cjl - I have an AMD X2 dual core 5600+ 2.8 MHz CPU

Then you don't have an FSB.
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a c 131 à CPUs
September 19, 2010 6:13:57 AM

cjl said:
Then you don't have an FSB.

True. But that "bus speed" in CPU-z (clock generator speed) which is 200MHz for modern AMD based systems is still what each component will use to base their speed off of with their multiplier. AMD uses hypertransport, who's speed is found by multiplying the "bus speed" by the NB multiplier. This is my impression of it. If anyone has any corrections, please let me know.
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