How does pcie 16x and 4x compare to 8x 8x motherboard

After a non-exhaustive look around, I found mid-way down this page:

http://www.anandtech.com/show/2084/2

that they claim less than a 1% difference for crossfire in X16-X4 vs X8-X8. Cards, chips, drivers are faster now and impose a greater load, so today's impact is likely at least a bit greater. Sorry, but that's the closest I could come - perhaps you can find more by googling and using respected review sites.

If your system is of similar age and speed to that in the article, you won't achieve a noticable difference. Personally, I wouldn't bother doing this unless I could pop my cards in cousin's board and actually see a difference.

crossfire what cards? I'm assuming this is PCI-E 1.0 slots rather then 2.0?

ok, so after looking around for awhile I found that it does have a performance hit in games with inconsistent fps compared to 8x 8x and 16x 16x pcie lanes

thanks for the replies

here's what I found: http://alienbabeltech.com/main/?p=2249&page=15