I'm hoping somebody here can point me in the right direction.  This is my fourth build and I'm pretty happy with how easy installation was.  I'm building a new rig, all new parts.  I'm unable to see any boot message on my monitor.
 
I had a problem with the RAM, which was resolved by reseating all the RAM modules.  (4x 8 GB)
I had a problem with no keyboard attached (which was fixed in five seconds).  
I'm now getting an "A2" POST CODE on the motherboard.  I unplugged all the drives, reset the CMOS, and still have the same problem.  
 
I am trying to view the output with a generic HDMI capable monitor.  The Z97 Classified has two mini-dp ports.  I'm using an Intel i7-4790K processor, which I understand has onboard graphics.  (I intend to get a 980 ti graphics card soon).  I've tried loosening the cooler (to no effect).  I've tried booting without the monitor attached and still get the same A2 code even after resetting the CMOS in between.  From others' posts I've read the monitor output with HDMI can be tricky, but I'd hope that if "headless" it would at least get to a booted state.  
 
As an experiment, I plugged in a USB drive and the code changed to 64.  
 
The parts:
 
 
CPU
Intel Core i7-4790K 4.0GHz Quad-Core Processor
Heatsink
Cooler Master Hyper 212 EVO
Motherboard
EVGA Z97 Classified EATX LGA1150 Motherboard
Memory
Corsair Vengeance Pro 16GB (2 x 8GB) DDR3-2400 Memory (x2 for my build, total 32 GB ram)
Power Supply
Corsair 850W 80+ Platinum Certified Fully-Modular ATX Power Supply
 
I don't know if I'm having one big or two unrelated problems.
(1) No video output / no compatible video signal.  Nothing shows up on my monitor, ever.  Can't reach the BIOS no matter what.
(2) Motherboard shows code A2 almost no matter what I do.
 
Any recommendations?
 
EDIT: SOLVED.  All issues resolved, though I think they're worth pointing out here to help others should they encounter similar problems.
 
1) A2 came up even though I was trying to reach the UEFI BIOS because though the documentation (found online) says to press the DEL key, it's actually F2.  Tested that with both 1.02, 1.07, and 1.08 firmware versions.  Solved this issue first before I could see any output.
 
2) Once I installed a video card, I could use the HDMI of the card output immediately.  It turns out Mini-DP can support HDMI, but not without it being enabled by the hardware.  HDMI and DVI use the same signal and protocol, so that kind of conversion is easy.  Display port uses a different signal and protocol.  It can optionally support a DVI/HDMI signal but this isn't always the case.  I'm surprised a bit that the Z97 wouldn't have this enabled given the price point. Of course, this board isn't aimed at people who aren't going to have graphics cards, so it's not really that big a deal.
 
On a side note, I bought both EVGA motherboard and graphics card.  Very happy, though when I tried to install the graphics card into the nearest PCIe (16x) slot, the shield on the back outputs was just too close and I had to put it into slot #2.  No big deal.

A2 means the motherboard is searching for a drive. Make sure you have the correct boot order in your BIOS.

Wow, thanks for the fast responses!  I'll try holding the CMOS reset button WHILE booting.  
 
There's no operating systems installed, nor are the drives even formatted.  I'd like to boot to a USB stick to install an OS (Arch Linux), but so far nothing shows up on the screen.  
 
I'm glad to hear A2 is a good sign.  I suspect it's the HDMI out that's really the issue.  The UEFI BIOS screen is probably there, I just can't see it.

Sadly I cannot say if this is a known problem with the 4790k CPU using a HDMI cable. I never used my onboard Intel graphics until I had already owned a DP cable but my motherboard does have a HDMI output on it. Whether the HDMI output works or not I can't say for sure.