After spending a week with the ASRock Z77 Extreme9, I have mixed feelings about it, when compared to other Z77 boards on the market. Thanks to a PLX PCI-Express bridge chip, the board enables the use of additional PCI-Express slots, a great feature for users who need support for three or more video cards. However, the oversight there is that the board claims to support quad-card SLI, but doesn't include a bridge to be able to do so, and the claims of five PCIe 3.0 slots are questionable to me. I found several PCI-Express 2.0 switch chips on the board, which simply aren't capable of PCIe 3.0 connectivity. I'm working on getting a bunch of PCI-Express 3.0 graphics cards, to further investigate this issue, but with my sample being and "Engineering Sample", this issue should be rectified with retail versions.
Power consumption was pretty good, and in general 3D performance was good too, but general computing performance seems to be on the low side. Honestly this wasn't something that appeared very obvious under normal usage for me, so while it sounds to be a big thing, it really isn't. Storage performance over all interfaces was very good, and truly, the biggest benefit of the ASRock Extreme9 just isn't shown in any type of testing, unless you populate all the PCIe slots.
Adding support for both quad-SLI and quad-Crossfire to a platform that usually only supports two or three cards with PCIe 3.0 connectivity is pretty amazing in and of itself, and if you want to run that many cards with Ivy Bridge CPUs, your options are pretty limited.
The whole package that the ASRock Z77 Extreme9 delivers is not bad. It's got great aesthetic design, the software is great, the overclocking is really really good, but I really feel that it's a bit overpriced at the moment. Of course, ASRock could pull off some magic and release a BIOS that fixes the performance issues, and then they'd have one killer product on their hands!