PCI-E X1 Cards

  • Thread starter Thread starter Clayton
  • Start date Start date
Clayton said:
Can a PCI-E x1 card work ok in a PCI-E x4 slot?
Click to expand...

Any PCI-E card can work in any slot where the x number is equal or higher
than the x number of the card. Basically, if the card x number is higher,
it won't physically fit the slot.
 
Paul said:
Yes.

According to Table 3 on page 7 here.

http://www.dell.com/downloads/global/vectors/2004_pciexpress.pdf
Click to expand...

I'm note sure where Dell have compiled this information from, but I suspect
that it may be the way they have implemented the PCI-E spec on their own
systems. The table suggests that an x4 slot will always be implemented
using an x8 connector, but this isn't generally true (it may be true of
Dell). x4 slot connectors exist and are used.

Photo of x1, x4 and x16 (plus PCI) here
http://en.wikipedia.org/wiki/Image:PCIExpress.jpg

In theory a PCI-E card should always work in any connecter in which it will
actually fit, only using those PCI-E lanes in the slot to which the card
connects. The PCI-E spec does allow motherboard builders to put larger
connectors on their boards and only wire a subset of the available lanes.
Thus Dell can put a x8 slot on their board and only wire 4 of the lanes. If
an x8 card is inserted, it should train down to use only the 4 lanes
provided (with a consequent impact on performance).

From what I understand, it has transpired that the PCI-E spec has managed to
include the obligatory ambiguity. It seems that the way the specification
has been worded, it can be interpreted that PCI-E slots can share lanes
between them (unintended AFAICT). Some motherboard manufacturers have
exploited this and it is not possible to fit a full compliment of PCI-E
cards to their motherboards. Once some lanes are taken up, they are denied
to the remaining slots.
 
I do have a Dell system and in the specifications it says x8 slot wired as
x4, whatever that means... I do have a x1 slot available but can not use it
as the graphics card is it's way
 
Clayton said:
I do have a Dell system and in the specifications it says x8 slot wired as
x4, whatever that means... I do have a x1 slot available but can not use it
as the graphics card is it's way
Click to expand...

I think I answered this point in another post. Basically this is something
Dell have decided to do (and is permissible).
 
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