Crossfire works on an 'unsupported' chipset (785G)...hunh?

I've been running a 5770 on my Asrock 785G for a while and finally decided to get a second one to do Crossfire with, partly since I've always wanted to do this since the Voodoo2 days but just never got around to it.

While the card was on the way from Newegg, I did some research about how to set it up, and I discovered that my motherboard's chipset is on the 'Unsupported' list, only capable of the now-irrelevant Hybrid crossfire. Bummer. Oh well. Am3 boards are comparatively cheap, so I ordered an 890GX one that was definitely supported.

The card came in last night and I installed it, putting the SLI bridge in place just for the hell of it. And when I looked in the driver settings...there was a Crossfire tab, and a checkbox to enable it. So I tried it out...the monitor connections on the secondary card stopped working (I assume this happens when Crossfire is engaged?), and 3d performance did seem better!

...so what's the deal about the 'supported boards' list, then? Is Crossfire just unsupported in the sense of 'Yes, it works, but don't call us for support', but in practice it works fine? Or am I just deluding myself about the performance increase and my second card is just sitting there doing nothing? (although if that's the case the drivers seem fooled too)

I'll probably keep the 890GX board when it gets here, but I was curious if anyone had run into this situation.

You can technically run crossfire, but not to its full potential in a 785g board. The 2nd slot is only running at x4 where as the 1st one is at x16. Normally in a crossfire you end up with x8 x8 or x16 x16 on the 890fx chipsets. With a 5770 the x4 probably isnt gonna hurt things, but if you had a 5870 it would be a bottleneck.

The 785 runs the first two slots at 8x/8x and the third at 4x. The 890 does the exact same thing.

After the recent testing that showed differences between 8x and 16x are miniscule, I'm not worried about bandwidth being an issue. And raw speed can't be the issue since the 785 and the 890 run at the same speed. There must be some other difference...