My brother is running an Athlon 800 on one of the original A7V boards. So, his FSB is 100(200). The bios offers the option of clocking the memory at either 1 or 4/3 of this speed. Since he has PC133 memory, it's set to 4/3. But, someone argued that unless the FSB is running at 133 as well, this won't make any difference at all. Why do they offer this option if it has no effect? Can anyone offer the truth on this matter? Thanks!
A7V memory clocking (4/3).
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Ok, here we go again 
. Just joined here just for the sake of responding to this post. I have a friend who shares your thoughts as to the Kx133 chipset's memory being limited to the 100 mHz bus. So what is the point of enabling PC133 support running at 133 if its just going to get bottlenecked by the 100 mhz bus? Sounds nice.
But here is the catch. The big thing about the Kx133 is that it has asynchronous memory transfer. That is the CPU-Memory ocmmunication is asynchronous. Unlike tranditional boards, like intels, where the memory/main board frequencies must match, the KX133 runs them independently. Thus allowing you to use at speed of memory (66/100/133...whatever). The North Bridge on the KX133 only acts as an interface between the memory and the CPU. This interface is asyncronous, and is not clocked.
Hope that clears it up, and hopefully someone else can verify this, as my friend still has trouble believing this.
Does Tom check these posts? I think he'd belive Tom.
Yamin
. Just joined here just for the sake of responding to this post. I have a friend who shares your thoughts as to the Kx133 chipset's memory being limited to the 100 mHz bus. So what is the point of enabling PC133 support running at 133 if its just going to get bottlenecked by the 100 mhz bus? Sounds nice.But here is the catch. The big thing about the Kx133 is that it has asynchronous memory transfer. That is the CPU-Memory ocmmunication is asynchronous. Unlike tranditional boards, like intels, where the memory/main board frequencies must match, the KX133 runs them independently. Thus allowing you to use at speed of memory (66/100/133...whatever). The North Bridge on the KX133 only acts as an interface between the memory and the CPU. This interface is asyncronous, and is not clocked.
Hope that clears it up, and hopefully someone else can verify this, as my friend still has trouble believing this.
Does Tom check these posts? I think he'd belive Tom.
Yamin
Just as a general reply. I have an Abit KA7 and yes I have tested it under both 100 mHZ and 133 mhZ and there is a big difference. At least that's what benchmark programs say. I can't really rell the difference in most applications, except for like Unreal Tournament and heavy applications.
Asynchronous memory transfer does come with a significant overhead. I believe the latency of asynchrounous @ 133 MHZ is about 15% larger than a synchronous system @133 MHZ. But overall, if you're comparing 100 MHZ memory with 133 MHZ memory, the 133 will be faster.
Asynchronous memory transfer does come with a significant overhead. I believe the latency of asynchrounous @ 133 MHZ is about 15% larger than a synchronous system @133 MHZ. But overall, if you're comparing 100 MHZ memory with 133 MHZ memory, the 133 will be faster.
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