^^ I don't think 6750 supports trifire. Its limited two max of two cards. Besides there isn't much difference at all xfiring two 6850's in x16-x16 or x8-x8. There is no bottleneck in lanes. Performance is same. Going for a third card will require more lanes.
@ devx
Stick with 2500k+z68 combo. Its a better deal in gaming than bulldozer. Get this eyes closed.
1. 3x CFX is possible wid 6750.
2. x16+x16 6850 CFX = x8+x8 6850 CFX -> HAHAHAHAHAAAAAAAAAA! Just read what you're saying!
3. As a platform Bulldozer + 990FX >> i5 2500k + Z68.
UPDATE - OPTX IS NOT FOR 8K ->
Joker said:in an ideal world...u should be getting 990fx + i5-2500k
in an ideal world, i wrote.
990fx is the better chipset out of the two. z68/sandy bridge has very few lanes. i think only 16 from the processor which means X8-X8 crossfire. tri crossfire is not even possible. and even if you add NF200 in z68...it will show worth only in tri fire/tri sli. for dual gpu, NF200 adds up slight latency.
and in reality...NF200 does not "magically" increase lanes in z68. it is still 16 lanes from the processor in sandy bridge.
i also consider A75 a better chipset than z68/sandy bridge and may be 990fx if you ignore pcie lanes. reason? all six SATA ports on A75 is 6gbps and USB 3.0 is also integrated into the chipset.
A single graphics card installed into the top slot will work in full-speed PCIe 2.0 x16 mode. If two graphics cards are in use, the graphics slots are x8 each. The third graphics slot has four PCI Express lanes, but if it's occupied, the following becomes unavailable: the eSATA and the additional SATA port, the onboard USB 3.0 connector, both PCI slots, and the back-panel IEEE1394 (FireWire) port.
@Joker - Hey bro... wassup?! and Im cool, only thing that has upset me today was that Alienware OPTX is not for 8k(I died a little inside when I got to know that! )
@Vickybat -
I built a machine for a friend about 3-4 days back so I know that it supports Triple CFX.