I've trying looking for a solution and have done a number of tests, and have isolated my issue... I think. I'd like to see what you all think.
Just upgraded to an Intel i7 4790k, an Asus Z97-E (just updated BIOS to latest version), and 32B of Corsair Pro Series DDR3 RAM (Not on Mobo QVL, but I don't think it's the issue, see below). I also have an MSI R9 290X 4GB Video Card.
I put everything together, hooked up all my peripherals, and excitedly pressed the power button. I excitement was quickly ruined when I couldn't get it to boot at all. It will get to the ASUS splash screen and then just hang.
After a lot of testing (the usual RAM tests, running on-board video, etc.) I came to discover that if any peripherals plugged in, it would not boot. I found this by removing all peripherals and resorting back to a PS/2 keyboard on boot. I was able to get to the BIOS, configure boot priority, install Windows 7 64-bit, and get it to boot all the way to the desktop. A small victory.
I started to reintroduce peripherals during boot, and found that it was only the USB3.0 bus that was the issue, not the USB2.0. I was able to plug in my Razer Lycosa into the two USB2.0 slots and it will boot just fine.
An interesting issue I found: While in BIOS, if I try to plug in a peripheral into the USB3 ports, it will lock it up.
Once my computer boots (or rather, once I get the "Starting Windows" screen) I can plug anything I want into the computer, including USB3 devices, and they will all work without issue. Knowing this, I hardly ever reboot my PC, and when I do, I have to unplug and replug in peripherals during boot at a very precice time after POST but before desktop to avoid the plug-and-play OS prompting a restart because of new hardware.
So my question is this: Is there some kind of setting on the Asus Z97-E that would cause this kind of boot issue? Would this be an issue with the motherboard, or an issue with the USB3.0 controller on the i7 (I had read somewhere that the controller was on the chip, not on the motherboard)?
Any insight would be appreciated.