# Relationship between AGP, FSB and PCI frequency ?

Discussion in 'Nvidia' started by Jean, Nov 3, 2003.

1. ### JeanGuest

Relationship between AGP, FSB and PCI frequency ?

Hello,
I try to find the relationship between those three.
Let's presume that we have a FSB at 100MHz.

AGP:
Is the frequency of the AGP1X bus is independent?
Then, is his value 66MHz?
Is the frequency of the AGP dependent with the FSB?
What will be the frequency of AGP1X?
What will be the frequency of AGP2X?
What will be the frequency of AGP4X?

Is the frequency of PCI always kept to 66MHz?
Any relationship between FSB and PCI?

Jean, Nov 3, 2003

2. ### LeeGuest

With some boards you can change the PCI and AGP fsb these are both linked
with the FSB and are all on the North Bridge (or is that South Bridge) heh
see your FSB is 100mhz and your PCI bus is 33mhz the PCI bus would be using
a ratio of 1/4 i.e. FSB/PCI ratio=PCI bus speed this is the AGP has a
slightly different formula if the FSB is 100mhz then the AGP ratio would be
2/3 so math = 100*2/3=66.66
Modern boards now can lock the AGP bus and PCI so that if you change the FSB
the PCI and AGP always stay in sync. LOL that was fun!
AGP1x 2x 4x etc refers to the amount of bandwidth the bus can carry i think
AGP4x is like 1.2gb/s bandwidth or something.

Lee, Nov 3, 2003

3. ### Sheldon RogerGuest

Depends on the MB. Most of the newer ones have AGP and PCI locked
allowing over clocking without having video cards and PCI devices
fail.

Sheldon Roger, Nov 3, 2003
4. ### Robert HancockGuest

It depends entirely on the chipset. I can tell you that the AGP bus speed
does not depend on the transfer rate (1X, 2X, 4X) in use, that only affects
the number of transfers that take place on each clock cycle.

Robert Hancock, Nov 4, 2003