Hi i'm planning on doing a Crossfire setup of 2 5850s but my motherboard is 16x 4x on the PCI-E Lanes. How should I go about setting that up? Will I get around 700 MH/s at least? Suggestions are greatly appreciated.
You need a decent card brand, first. I was only able to get 700+ MH/s on ASUS cards because nothing else would OC high enough. I tried some Visiontek cards, but I was simply unable to get past 600 MH/s because the cards are low-quality.
I was wondering about PCI-e bus lane multiplier reductions, too, but it turns out it isn't an issue in mining.
To get 710 MH/s, I used the poclbm miner with flags "-v -w128." Overclocking's dead-simple in Afterburner. I was able to increase my core clock speed (and this is where brand's very important) up to 912 MHz on one card, 925 MHz on the other I'm using. I also downclocked my mem speed to 319 MHz (see here). Your max OC will vary depending on how lucky you get with the quality of your particular card.
Im doing 410mhash per hd5850 at the following, 995/180 , the difference between memory @ 300 and @ 180 is about 10mhash per card, so give that a try rather than your memory @ 319.
I used RBE to biosmod the core-mem so no software required.
