Pci-e x8 help

[Guest]

im am looking to build my first computer. the problem that i am running into is, all the motherboards that are in my budget [~<100$] that do have 2 pci-e x16 slots, only one is true x16 and one slot only performs @ x8. so will the x8 slot run a current mid range GPU [gts250 or HD4850] in sli/Xfire mode? will there be a performance disadvantage?

 

[yellosnowman]

If you are talking about a P45 chipset then according to what I've seen, the difference is no that high.....
It was around 5%~10% difference between the P45 and the x48...... I don't think its worth that much money for a x48 especially for mid range graphics card. Get a P45 and a HD4850x2 which is same/better than two HD4850 in CF.