EVGA X58 bottom PCI-E slot

I am thinking about getting the EVGA X58 3X SLI motherboard. I do plan to use a PCI-E X-Fi card and I am wondering what will happen in the following configuration.

I know that using 2 PCI-E video cards in the first two full PCI-E slots will have them both running in x16. From what I understand, utilizing the third full slot for 3X SLI will result in x16/x8/x8. There is a x1 slot but unfortunately it's sandwiched between the first 2 full PCI-E slots...

If I were to put the x1 X-Fi card in the bottom PCI-E slot, what would be the impact on the first two slots? Would they be running in x16/x8 or would they both be x16?

Alternatively, would another X58 board like the ASRock Supercomputer allow this (x16 for 2 video cards and a x1 audio card)? If I remember correctly the four slots there are paired in some fashion.