5570 running on a PCI-E 16x slot with 4x electrical??

[Delphium]

Hey folks, I am in the process of building a machine for work that will run with 4x 5570's, however due to the limited number of authed supplyers for work, I am limited on the choice of mobo's and gfx cards I can use.

As such I am currently looking at an AMD/ASUS (crosshair formula IV) mobo that sports 4 16x slots in a 16x,8x,8x,4x configuration.

So I just wished to know if a 5570 will function (admitedly not at full capacity) on 4x pci-e lanes.

I have read reports online stating that crossfire has been known to work on a 16x,4x configuration, however I am unsure if this stands true still for the 5x series.
If anyone could confirm this works I would like to hear from you, perhaps Dave Baumann or SunSp*t may be able to confirm this at all?

Many thanks.
Delph

[BRPunk]

I don't know the answer, but I'm curious what purpose this machine would serve as quadfire has been known to be massively unstable.

[Delphium]

Not running quadfire, its just a highly multi headed machine.
I suggested a pair of 6x display port cards, but the budget does not cover this, nor does the limited list of supplyers supply this product.

[Dave Baumann]

Its not something we actively test for at an individual board level, but PCI Express operating on a reduced number of lanes is part of the specification. Techpowerup actually runs a few graphics cards tests looking at operation on reduced numbers of lanes, and here's one in the same family at the HD 5570:

http://www.techpowerup.com/reviews/AMD/HD_5870_PCI-Express_Scaling/

[Delphium]

Many thanks Dave for the information and link, it looks like it should work out just fine :)

Cheers.
Delph.

[Delphium]

After building the system today I can confirm that all 4 cards function 100%, even the one in the 4x electrical socket. :D