Quote Originally Posted by zalbard View Post
You need two NF200 for 4-Way SLI. Maybe it's going to be different for 990FX, don't know. But so far you do need them.
Quote Originally Posted by XRL8 View Post
990FX has enough pcie lanes for four way sli (4x8) ,and they arranged to have it on their chipsets(licensed).So what would be the use for nf200 ? 4x16 maybe, but thats overkill.
Quote Originally Posted by zalbard View Post
It isn't about having enough PCI-E lanes. Have a look at R3E (or R3B), for example. It has enough slots and enough bandwidth, but does not support 4-Way SLI without an extender which contains an NF200 chip. It's Nvidia's requirement.
Nvidia has already been working with Amd on this project. It may be the NF200, but it might just be an on-chip variant specific to Amd.

However, one thing to clear up. I felt like I was pretty specific in my first post that 4-way and 4-card are not the same thing. NF200 is not required for 4-way SLI since you only need two PCI-e lanes to run two, dual-gpu cards. Just be conscious of this difference.