sadly I'm not an expert in PSUs, I have some experience with far bigger PSUs (those for gaming rigs) but that's it.
Being this a forum though, the info is out there for others to comment too.
There's not a lot of clearance between the bottom of the PSU and top of the CPU fan, so anything larger than this PSU is not going to work as this was a tight fit already.
hmmm, this means relatively bad air circulation unless the PSU is sucking up the air from the CPU. Make sure that temps in all your hardware is stable and relatively low. Although if you followed that guide you linked it's safe to assume that it's not an issue.
Good thinking on hiding one from the BIOS, though. I'll give that a shot.
Just a (probably needless) clarification, the keyboard "hidden" from the BIOS is seen only by Windows 7, so if you want to alter bios settings you need to use the other.
I'd personally hide the "mini-size with a built-in trackpad for HTPC use", because it sounds the most complex (while the full-size keyboard is much simpler), also, if you have a powered Hub (a Hub with its own power supply) you can make sure that the device isn't taking its power from the USB (=from the PSU).
although now that you told me about the Traktor, it's the one I'd look at first. sneaking suspicions....
So does USB 3 do something different with power?
USB 3.0 is supposed to deliver a twice the power of USB 2.0. And even then, not all USB are equal.
The USB 2.0's power should theoretically be 500 mA per integrated port, and 500 mA per USB header
(a header is a bunch of pins on the mobo that allow you to connect cables to run usb ports integrated in the case). It's the same for USB 3.0 (they just have 900 mA of output).
Looking at the Intel page
about your mobo I see "four back panel ports, four ports via internal headers and two ports via Mini PCI Express* connector". so you have 4 ports with full powaaa!, 4 ports you must check to see how much headers per port (usually is one header per 2 ports, so its a half powaaa! port) and a couple ports on a friggin mini-pci express connector that I have no idea how power can give.
Most high-juice devices like USB HDDs say (or said in the past) "please attach this to the back usb ports". that's to ensure that the device gets the full powaaa! it needs.
Rearrange your devices to take advantage of this "detail" and see if there are still issues.
Then again by looking at the manual
they say there are 2 yellow "High current USB" on the back, 2 normal usb on the back and other weirdness. *facepalm* what the heck is that....
Something like that would prompt me to use my multimeter
and find out what is the actual output on each port.
Look what ports are "high current" according to the manual and keep in mind the things about headers I said when you rearrange your devices.
The Traktor needs the best 2.0 ports you have, the integrated one from the back they colored of yellow (the "high current" ones).
Keyboards and mice usually don't need a whole lot of power, but you said you have a gaming one and a keyboard with touchpad, so those two must be on different headers at the very least.
In fact, the only thing that's died is the Traktor Audio 6 on USB 2. I'd put the Traktor box on USB 3 and keep one of the kybds unplugged and everything would be great except according to many users on the Native Instruments forums this device hates USB 3.
Wait a sec. Just googled it and yeah, sounds relatively power-hungry. What other devices you have other than the 2 keyboards, the mouse and this thing? Because it may very well that you did connect your stuff in a way that saturated the USB power output (see above), and this means something got the shaft (was left unpowered).
Their product page seems to say that it should accept a separate power supply "Additional Power Supply (9 V, 1200 mA) will be available separately for using Direct Thru mode." (you can use generic power supply if they have the right connector in their inventory and can be set at the right V and produces the required mA or more), otherwise you can plug it to a powered USB hub.