PCI Express explaination??

[khicon]

Expansion Slots

* 2 PCI Express x16 slots
* 1 PCI Express x1 slot
* 1 PCI Express x4 slot
* 2 PCI slots


Can someone explain the the difference about PCI-E x1 and PCI-E x4? I know x16 are for video card and regular PCI slots are for addon cards but the other 2 are unknown to me.

Thank you.

 

[Dahak]

the way pci express works, is there are lanes, for the bandwith, so a x1 slot only has 1 lane, and is designed for more general items like sound, lan, cards.
a x4 slot has 4 lanes on it to deliever more bandwith, x16 slot is the same as well, with 16 lanes.

aslo all slots are backwards compliant so if you have a x1 card, it can go into a x4 slot but will only be using the x1 bandwith.

x1,and x16(for graphics primarily) is what you will see on most desktop boards. x4,x8 will tend to be more server focust for high end raid, and fiber

 

[sixscrews]

PCI Express uses serially encoded data streams which can run in groups.

x16 means there are 16 lanes being used.

X1 means only one
X4 means four

Ad nauseum

The chipset used determines the number of lanes available. Most chipsets available today have 20. 16 of these are used for the video, leaving four.

If a board has a video slot (x16) and an x4 slot it's maxed out when both are populated. If the board also has an x1 slot either the x4 or the x1 can be used, not both (I'm a little shaky about this - there might be provisions for sharing the lanes but they both can't have exclusive access at the same time).

The SLI system uses 8 lanes for each GPU, still using the 16 lanes for the video, by the way.

Hope this helps.

ss

 

[khicon]

Thank sixscrews and Dahak for the info.. I've also google it and found some helpful info as well.... now it is more clear what those slots are use for.

 

[Fisher999]

Originally posted by: sixscrews
PCI Express uses serially encoded data streams which can run in groups.

x16 means there are 16 lanes being used.

X1 means only one
X4 means four

Ad nauseum

The chipset used determines the number of lanes available. Most chipsets available today have 20. 16 of these are used for the video, leaving four.

If a board has a video slot (x16) and an x4 slot it's maxed out when both are populated. If the board also has an x1 slot either the x4 or the x1 can be used, not both (I'm a little shaky about this - there might be provisions for sharing the lanes but they both can't have exclusive access at the same time).

The SLI system uses 8 lanes for each GPU, still using the 16 lanes for the video, by the way.

Hope this helps.

ss

Very well said :light: