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?