Previously working Windows 7 system won't boot after cmos reset

I'm looking for help to be the heroic big brother here, because my brother has managed to stump me with this one:

Windows 7 Home Premium
Asus P8Z68-V LX Motherboard
8GB Corsair XMS3 memory (2 x 4GB)
(Two week old) NVIDIA Geforce GTX-970
1 TB HDD RAID Mode, but set as non-raid archtechture (data intact and fully accessable)
32 GB SSD used as intel smart response RAID0 Cache (raid cache currently disabled)

Filled with confidence by after recently installing his new graphics card mostly by himself, my brother the power gamer was attempting to further minmax his rig by tinkering with his BIOS settings, aiming at a mild overclock. He decided to start by switching his system from the settings his custom build came with, to the generic "turbo" profile in the Asus EzMode bios.The computer apparently objected to this decision, and refused to boot. He then set it to normal mode, and it also refused to boot.

At this point I was introduced to the situation with the phrase "I think I broke my computer", and we had a discussion through a facepalm about the wisdom of changing settings when you don't know what they do and the current settings are working just fine.

After some quality time with the BIOS I think managed to undo most of the damage: I switched the hard drive type back to raid, set the PCI back to auto from low power mode, turned off the power-saver settings, set the boot to ignore the card reader ports, and deleted the potentially corrupt scratch cache from the RAID console. Didn't mess with the overclock settings, because he went back to normal mode which should theoretically have disabled any failed overclocking from turbo.

But its still not fully up and running.

Boot types that do not work:

• 
  ■start windows normally- freezes at pulsing windows icon (which ceases pulsing after about a minute, should that tell anyone anything.) if you leave it for a while (~5-15 minutes) it eventually reboots or turns off.
  ■launch startup repair: shows old pixel style windows icon above green loading bar for about 2 seconds before cutting to a black screen with no cursor. Again, if you leave it sit like this for a while it will eventually reboot or turn off.
  ■system repair disk, run normally: same as the startup repair from disk- green loading bar for a couple seconds, then black screen. Eventually reboots or turns off.
  ■ Trying to boot from the F8 menu in "driver signatures disabled" mode gets a BSOD of the "IRQL not less than or equal type" Don't know the code because I only found out afterward that its the bit in parenthesis that matters, not the 0x0000000A bit. Don't like doing those on purpose, but when I tried it again just to be sure it does recreate the same error so I could get it if its necessary.

Running the system repair disk in safe mode through F8 menu launches into system repair options with no fuss at all. System repair detects the windows installation with no issues. Running startup repair seven or eight times returns no problems detected. Follow up boot same gets black screen same as before. Tried last good configuration, same thing.

After this, I tried the F8 menu for the main disk. Sure enough, the computer boots in safe mode, and runs fine. Hardware appears to be intact by all diagnostics I can conduct in safe mode. I also know what hardware failure looks like very well, as last year I had to frankenstein my digital art rig through two separate motherboard failures (one to old age, the second to a lightning strike) and a defective memory card. The computer is showing no behavior of that sort- no lag, no graphics glitches, no memory or write error issues, no blue screen crashes. It looks like the problem is somewhere between the BIOS settings and the drivers.

Other things we've tried:

• 
  ■ All drivers checked in "safe mode with networking" test as intact and up to date (I'm trusting window's judgement enough to not mess with that can of worms until I get a second opinion)
  ■ Clean install of freshly downloaded graphics driver did nothing.
  ■ sfc scan fixed a few files, still no boot.
  ■ chkdsk /f says the drives are fine.
  ■ Memory tests as good.
  ■ disabling legacy USBs does not help.
  ■ disabling card reader ports does not help
  ■unplugging all drives except for C: drive does not help.
  ■ plugging in drives to different sata ports does not help.
  ■ glaring at motherboard muttering about hammers does not help.
  ■ running sfc again detects no integrity problems.
  ■ running system repair disk another seven or eight times detects no problems
  ■ digging through event logs shows nothing out of the ordinary.
  ■ System still does not boot normally.
  ■ System does not boot in clean boot mode.

System will always boot on the first try in any type of safe mode and runs perfectly stable. It will not boot at all in normal mode. And the system seems entirely unconcerned by the situation.

At this point, I'm frankly stumped.
I have a hunch there's probably some tiny problem or two that I'm missing.
Anyone know of something else we can try before I tell him he's about to be the owner of a shiny new Windows 7 disk so he can reinstall?