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FSB & Proc speed???
- Thread starter patroller
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In the older days (pre-Pentium III), the FSB and Memory bus (RAM Speed) usually matched. So if you had a CPU with 66MHz frontside bus, chances are that you also had PC66 SDRAM.
However, that wasn't always the case. The two don't have to match. For example, there were chipsets out there that supported the newer Northwood Pentium 4's that had a 533MHz FSB, but only used PC2100 (DDR 266MHz).
~cdogg
[tab]"The secret to creativity is knowing how to hide your sources"
[tab][tab]- A. Einstein
However, that wasn't always the case. The two don't have to match. For example, there were chipsets out there that supported the newer Northwood Pentium 4's that had a 533MHz FSB, but only used PC2100 (DDR 266MHz).
~cdogg
[tab]"The secret to creativity is knowing how to hide your sources"
[tab][tab]- A. Einstein
you need to get 66mhz SDRAM for that PC. FSB is the bus speed that the motherboard runs at. Meaning:
66mhz bus says the mother board is runnig at 66mhz and the ram will run at 66mhz and the processor will run at 66 x the multiplier. ie 66 times a (3x)multiplier means you have a 200mhz processor.
now days you can buy 133mhz ram and it wills step down to 100mhz on a 100mhz bus. but older machines you have to match your ram almost identical to each other and match the bus speed.
66mhz bus says the mother board is runnig at 66mhz and the ram will run at 66mhz and the processor will run at 66 x the multiplier. ie 66 times a (3x)multiplier means you have a 200mhz processor.
now days you can buy 133mhz ram and it wills step down to 100mhz on a 100mhz bus. but older machines you have to match your ram almost identical to each other and match the bus speed.
cdogg is correct. YOur board has a 66mhz bus and should use 66mhz RAM. You MAY get pc100 to work on it. You might not. The older RAM should.
As for the confusion with the newer cpu's and bus speed, both AMD and intel use a doubler for the CPU. My bus runs at 133 but my Athlon 1.4 GHZ has a 266MHZ rating. Same thing for cdoggs example, that P4 board runs at 266 but the CPU timing is doubled to 533, or close to it.
Jon
There is much pleasure to be gained from useless knowledge. (Bertrand Russell)
As for the confusion with the newer cpu's and bus speed, both AMD and intel use a doubler for the CPU. My bus runs at 133 but my Athlon 1.4 GHZ has a 266MHZ rating. Same thing for cdoggs example, that P4 board runs at 266 but the CPU timing is doubled to 533, or close to it.
Jon
There is much pleasure to be gained from useless knowledge. (Bertrand Russell)
jhall01,
You are correct in this case. However, I just wanted to point out that the FSB doesn't control the memory bus. The FSB only concerns the connection between the CPU and the chipset - memory has its own connection. Back in the day of the Pentium and Pentium II, the FSB and memory bus were locked at the same speed to simplify things. Newer boards have a separate setting for the memory bus, which is now totally independent.
Do you remember the first P4's that used PC-133 SDRAM? Aside from it being a disaster performance-wise, the memory bus was clocked at 133MHz, while the P4's FSB was clocked at 400MHz (100MHz x 4). That's just one example.
Because of latency, you usually want the FSB and memory bus to match. But the point is that it doesn't have to match...
~cdogg
[tab]"The secret to creativity is knowing how to hide your sources"
[tab][tab]- A. Einstein
You are correct in this case. However, I just wanted to point out that the FSB doesn't control the memory bus. The FSB only concerns the connection between the CPU and the chipset - memory has its own connection. Back in the day of the Pentium and Pentium II, the FSB and memory bus were locked at the same speed to simplify things. Newer boards have a separate setting for the memory bus, which is now totally independent.
Do you remember the first P4's that used PC-133 SDRAM? Aside from it being a disaster performance-wise, the memory bus was clocked at 133MHz, while the P4's FSB was clocked at 400MHz (100MHz x 4). That's just one example.
Because of latency, you usually want the FSB and memory bus to match. But the point is that it doesn't have to match...
~cdogg
[tab]"The secret to creativity is knowing how to hide your sources"
[tab][tab]- A. Einstein
True, I wasn't being detailed enough but i didn't think it mattered too much. You can tell they run on different bus speeds because you may have a faster FSB speed than the ram currently available which is true with the latest boards and processors compared to the ram bus speed. I just wasn't being detailed for someone new to hardware.
Very good point cdogg.
Very good point cdogg.
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