http://www.bit-tech.net/hardware/motherboards/2010/04/27/msi-890fxa-gd70-motherboard-review/1

Could somebody explain to me what does "Expansion slots Four 16x PCI-E 2.0 slots (two 16x or four 8x)" means according to mining? Does it means that if I will use four HD 5870 then they will work on only half of their performance?

It has no impact on bitcoin mining... Just on playing video games

x16 to x8 doesnt even have an impact in games