870 Crossfire x16x4 or x8x8 ?

travisbicks

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Sep 18, 2010
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I’m building a budget gaming machine for which I have bought a 5770 graphics card. My original choice of motherboard was an Asrock 870 Extreme3. I’ve had to RMA the board and I’m now wondering if I should stick with my choice or look for an alternative.

The selling points for me were the advanced features of the 870 for the budget price and the advertised Crossfire ability of x8x8. I’m not considering running Crossfire at the moment but would like to keep it as an upgrade option. I’ve read that with two 5770s the performance difference between x16x16 and x8x8 is marginal.

However what’s now puzzling me is that I’ve since read that the 870 chipset only supports crossfire at x16x4.

So my questions:-

1) Does the Asrock 870 Extreme3’s ability to support Crossfire at x8x8 involve some kind of work around or compromise that will mean an unacceptable loss in performance compared with the “true” x8x8 of other chipsets?

2) Are there any other 870 boards that can also support Crossfire at x8x8?

3) Would Crossfire at x16x8 be noticeably worse than at x8x8?