ASUS 990FX R2.0 will only power on with MemOK button

[MisterDoug]

I purchased some new parts to build a computer:
ASUS 990FX R2.0 motherboard
Corsair Obsidian 450D ATX case
AMD FX-8350 Black Edition 8 core 4.0Ghz processor
Corsair Hydro Series H105 Liquid CPU cooler
EVGA GForce GTX 970 video card

From my previous computer, I took the following:
Raidmax Hybrid RX-730SS 730Watt ATX power supply
4x4GB G.SKILL Ripjaws X Series DDR3 1866 (PC3 14900) RAM
Optical drive and hard drives

After putting it all together, it turned on fine, but didn't recognize the optical drive. I forgot to plug it in. I turned it off, opened it back up, connected the power and SATA cables to the optical drive, but the power button on the case no longer works.

It doesn't appear to be a power issue, from what I can tell. When I turn on the power supply, my ethernet light begins to flash, there's a strong yellow power light on the motherboard, and USB ports have power.

The only way I can start it up is by pressing the MemOK button on the motherboard. It states that memory tested OK, and it works great from there. If I reboot the machine, no problems. But if I shut down, I have to use the MemOK button again.

The power button on the front appears to do nothing. When I press it, I can feel it click, but there's no response from the motherboard - no lights come on, the power light doens't go off, nothing changes.

The only odd thing I noticed is the RAM. Once I'm up and running, CPU-Z shows the RAM running with Max Bandwidth of PC3-12800 (800 MHz) for all 4 slots. I've removed and re-seated all RAM chips, no change. I have not tried running on less than all 4 chips, but that's my next step. I intend to get new RAM as I can afford it, hopefully bumping up to 32 gigs eventually.

I've cleared CMOS by switching the jumper on the motherboard for 5-10 seconds, as it says in the motherboard manual, but that didn't change anything, other than reverting my clock and BIOS settings.

I would greatly appreciate any input. I can provide any additional info needed to troubleshoot. Thank you!

 

[Calvin7]

FX CPUs only support 1866MHz memory with one DIMM per channel.
1600MHz speed is supported with 2 DIMMs per channel.

DDR3 1600 (PC3 12800) is what your memory is at now with 2 DIMMs per channel.

Higher frequencies require overclocking. Here is an example, "jumping my cpu/nb frequency to 2400mhz from 2200mhz".
http://www.tomshardware.com/answers/id-1752459/dominator-platinum-8320.html

Also, mixing multiple memory kits frequently causes compatibility problems, such as being unable to boot or unable to operate at rated specifications.

 

[MisterDoug]

That would explain the RAM speed, even when I went into the overclocking section on the BIOS and tried to change it from Default to the rated speed of the RAM, it still showed as DDR3 1600.

That doesn't explain why my power button doesn't work.

So... another thought. Maybe the power button on my case is just broken? I switched the wires with the Reset switch, in an attempt to test that, but that didn't work to power on the computer either.

I also checked the motherboard BIOS - it's at the latest version.