16x+16x PCI-E vs 8x+8x and 16x+4x, does anyone have comparisons ?

[Vogon]

Links to articles, or knowledge, both appreciated
I am interested in what (if any) difference there is.
Also dual 16x is theoretically the best, but which of the other 2 would be second best ?

Thanks

 

[Vogon]

When you consider right at the end of AGP, even the bandwith of 8x AGP was never fully used, it doesn't suprise me.
Thats why I asked about this, as I feel it might be the same scenario.
If you want a crossfire board, the forthcoming X38 chipset offers dual 16x, but current boards are either 8+8 or 16+4, I dont know if either of those is better than the other even
Thats why I was hoping someone could enlighten me