AGP Bus question

[Zoio]

Bus | Width| Clock Speed | Transfer Rate
AGP | 32 | Depends on CPU speed (66 MHz is typical) | Up to 533 MB per second

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i just came across a table like that, im just a bit confused.

Reffering to CPU Clock speed, im assuming that they are talking about System Bus? 66MHz
. would a higher system buss such as 133MHz equal to 800MB/s ?.

 

[mavalpha]

Not exactly. Ideally, AGP is 66.66MHz. However, chipsets that don't have an AGP(/PCI) lock calculate the AGP bus frequency by applying a ratio to the processor's FSB (or HTT, for A64). IOW, a 133FSB chipset overclocked to 150MHz without a lock would have an AGP frequency of 75MHz. The table is outdated, because AGP8x allows 2.1GB/s to the video card. However, all AGP slots only allow 1x speeds to retrieve the information from the graphics card (provided they use convential PCI writes, which nVidia says they circumvented by the end).

 

[Zoio]

Thanks man really appreciate it, all cleared out on it now.

 

[Zoio]

Not exactly. Ideally, AGP is 66.66MHz. However, chipsets that don't have an AGP(/PCI) lock calculate the AGP bus frequency by applying a ratio to the processor's FSB (or HTT, for A64). IOW, a 133FSB chipset overclocked to 150MHz without a lock would have an AGP frequency of 75MHz. The table is outdated, because AGP8x allows 2.1GB/s to the video card. However, all AGP slots only allow 1x speeds to retrieve the information from the graphics card (provided they use convential PCI writes, which nVidia says they circumvented by the end).

is there a certain calculation to get the 2.1GB/s

 

[UncleMacro]

Is there a certain calculation to get the 2.1GB/s

It's 66MHz*8*4.

66MHz : the clock rate
8 : AGP 8X is octuple pumped (8 transfers per clock)
4: bus is 32 bits wide.