Dual PCI-E 2.0 running @ 8x each equal to PCI-E 1.x at full 16x?

[cbn]

I am considering a very cheap Asrock P45 mobo that apparently has PCI-E 2.0 capable of Crossfire at 8x and 8x (instead of 16x and 4x)

Would running each of those PCI-E 2.0 lanes at 8x be equal to running a PCI-E 1.0 at 16x?

I am just wondering because I am thinking of running two HD4770 ATI radeons and I am pretty sure each one doesn't max out a PCI-E 1.x slot running @16x.

 

[Sylvanas]

Yes, PCI-E 2.0 8x is equal to PCI-E 1.1 16x. There used to be a sticky on the motherboard forums explaining in the bandwidth of differing bus types, but its not there anymore .

 

[cbn]

Originally posted by: Sylvanas
Yes, PCI-E 2.0 8x is equal to PCI-E 1.1 16x. There used to be a sticky on the motherboard forums explaining in the bandwidth of differing bus types, but its not there anymore .

That is interesting because I have seen articles comparing P45 Crossfire (PCI-E 2.0 @ 8x,8x) to X48 crossfire (PCI-E 2.0 @ 16x,16x) with HD4850s and the Crossfire on the P45 doesn't do nearly as well as the X48 (especially at higher resolutions).

But a 4850x2 in a single PCI-E 2.0 slot (essentially Crossfire @ x8,x8) does a well as two HD4850s in separate PCI-E 2.0 slots?

Therefore I am assuming something else within the mobo is limiting Crossfire Scaling with P45. Does anyone else have info regarding whether this is true or not?