I am now in trying to decide between a P67 mobo in my price range and a Z77. I am leaning towards the Z77, but one feature of the Asus P8P67 WS Revolution is that it offers 4 PCI slots and in a 2 card configuration, it is able to offer x16 speeds. The Z77 board from MSI offers Crossfire support at x8 in a 2 card setup. My question, let's say one were to put two Radeon HD 7970's into Crossfire on the Z77 board, would the reduced amount of channels make a difference that makes a difference for practical purposes?
There's some really interesting results here and if we begin to dissect it a bit we can understand what's going on a bit better. Sometimes we see the x16 / x16 via the NF200 chip run faster, while other times we see the x8 / x8 setup via the native Intel chip run faster.
There seems to be a constancy, though, when we're under high VGA load. Not hitting a CPU brick wall or anything like that, the x8 / x8 via the native P67 chip is a faster setup. When we see lower resolutions and the CPU play a larger picture, the x16 / x16 via the NF200 is faster.
So what's faster? You know, there's probably not a clear winner when it comes to overall speed. The better question would be; so what's better? Well, the x8 / x8 setup that ASUS choose to implement seems to be. Yes, it's not always faster, but when we're all about the video card power, it is the faster setup. The times we see the NF200 setup come out ahead is when we're looking at benchmarks with really high FPS.
We can see under intensive situations like Aliens vs. Predator and Unigine Heaven, the x8 / x8 via the native P67 chip is the better option. When it all comes down to it, there's little difference between the two setups. The decision for ASUS to go down the x8 / x8 path via the Intel chip instead of the better looking x16 / x16 NF200 path seems to be the right decision.
It's so easy to get caught up in the numbers, but they only paint part of the picture. What I'd like to see ASUS do is highlight the x8 / x8 benefits a bit more, because at the moment there's a lot of confusion about the x8 / x8 dual GPU setup specification. With the NF200 present most people think that it's simply an error on the ASUS website. It's not, though, and is clearly intentional and for good reason.
Some interesting results here today and hopefully we've helped clear some of the confusion up around the x8 / x8 vs x16 / x16 argument on the P67 / Z68 platform.
You should get the z77 board because the z77 chip is way better than the p67 chip. If you put an Ivy Bridge cpu in the z77 board it will allow you to use pci-e 3.0, which when ran in 8x/8x offers the same bandwidth as pci-e 2.0 16x/16x. Also 2 radeon hd 7970s running in pci-e 2.0 8x/8x really wont be bottlenecked when gaming.