Upgrading, which Motherboard?

DireMe

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Sep 4, 2013
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Hey. I have an AMD FX-6300 on a rather new built pc but want to upgrade Motherboard. I Might be ordering tonight, which would be nice. But I currently have a 970-a chipset and want to get a 990FX that supports SLI for two 760s in the future. I am going between
MSI 990FX-GD65
ASUS M5A99FX Pro R2.0
ASUS Sabertooth R2.0

I know Sabertooth is the best, but also 25 euros more than the other two. And then is my primary question. What speed does the PCIe give in SLI? I know Sabertooth gives both cards x16 but the other two? Can't find that info anywhere... Do they get x16 on one card and x8 on the other? Thanks