PCI vs. AGP vs. PCI Express

JoLLyRoGer

Diamond Member
Aug 24, 2000
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Will inserting a standard PCI card slow the FSB of the system to 66Mhz and ultimately defeat the advantages of faster AGP and PCI Express cards?

Similar to the way the old ISA cards would slow down the PCI devices?

Or am I just out in left field here?
 

biostud

Lifer
Feb 27, 2003
19,449
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AFAIK the PCI run on a different bus than PCIe and AGP, so no limitations.
 

neutralizer

Lifer
Oct 4, 2001
11,552
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The PCI card runs on a divider from the FSB to ensure that it runs at 66 Mhz while maintaining the full speed of the FSB so it shouldn't slow down the FSB.
 

imported_Ned Flanders

Senior member
May 11, 2005
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Inserting a PCI card into a PCI slot in either a motherboard capable of PCIe/AGP connections WILL NOT slow down anything. They run on separate busses.
 

JoLLyRoGer

Diamond Member
Aug 24, 2000
4,153
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Well thanks for the replies guys. I'm still trying to learn how all of this stuff interconnects and relates to one another.

So basically I'm gathering that PCI, PCIe and AGP all run on their own busses.

It also seems that PCI and PCIe and USB all connect into the Southbridge along with SATA, while AGP connects to the Northbridge. So I'm assuming there are different multipliers/dividers for each bus to keep the FSB humming. Is this correct? Otherwise the Southbridge would have to gear down to the slowest device connected to it thus slowing everything else down too. Correct or no?

Also, what about congestion on the Southbridge, can that effect overall system performance?
 

phatboye

Junior Member
Feb 15, 2005
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Although putting a PCI card in will not affect your AGP or PCI-e cards it will slow down other PCI cards since all PCI cards share bandwidth.