Hi.
 
New builder here. Full system specs at the bottom of this post.
 
Problem: I'm having trouble with my PC not booting up to BIOS. Motherboard seems to power on (some LEDs come on), case and CPU fans come on, but there are several red error LEDs: memory_error, pe4_error, pe2_error. Additionally, the debug code display on the board (not sure what it is called) is cycling quickly through many numbers or letters, too fast for me to tell which codes they are. Nothing appears on the monitor. Monitor confirmed working with another computer.
 
Here's what I've tried. Restarting between each attempt. 
 
Switched from BIOS 1 to 2 and back to 1 -> nothing on screen, same error LEDs. 
 
Startup on BIOS 2 -> nothing on screen, same error LEDs. 
 
Tried different video outputs: motherboard video outputs (HDMI & DP) and video outputs from two GPUs (both confirmed working on separate PC). -> nothing on screen, same error LEDs. 
 
Removed GPUs & restarted -> nothing on screen, same error LEDs.
 
Swapped RAM. Tried three different single 16GB DDR4 Sticks, all in slot 2. Tried two sticks in slots 2 & 4 -> nothing on screen, same error LEDs.
 
Removed CPU and checked for bent pins - from what I can see by eye everything looks fine in the socket and bottom contacts of CPU. Brand new CPU & motherboard. Checked for anything that could be shorting it, like loose screws or wires.
 
Tested second power supply (corsair CX650M, confirmed working to power 2 GPUs on separate computer) -> nothing on screen, same error LEDs
 
Removed both NVMe M.2. drives so I only have CPU + cooling, 1 stick of RAM, ATX_PWR_8P, ATX_PWR_24P -> nothing on screen, same error LEDs
 
Turned off and pressed RESET CMOS button -> nothing on screen, same error LEDs
 
I'm at a loss of what to do. I've ordered some new memory sticks, but given that it failed with all 3 that I have, I kind of doubt that is the problem? Any help would be much appreciated! Thanks!
 
Full system specs:
 
Motherboard: Z370 FTW
CPU: Intel i7-8700k 
Cooler: Hyper 212 Evo
RAM: Micron MTA36ASF2G72PZ-2G1A2
 
Storage: 2 x 970 EVO NVMe M.2
GPU1: EVGA GTX 1070
GPU2: EVGA GTX Titan X
 
PSU: EVGA Supernova 1000G3
 

I think I remember some of those Red LEDs are Normal  & Not indicating an Error --> did you check the manual ?
 
What does the "debug" LED stop On  = ?
 
Only use 1 GPU - until you get your OS loaded
 
Use your iGPU  (the one in the CPU)  HDMI at I/O back panel

When I installed the OS on my Z370 FTW I use only on board.
After the OS was Installed and All Updates were installed I then Installed my GTX 1080 Ti FTW3 Hybrid Card.
I installed the GPU Booted into the Bios and then Disabled the On Board and set the Graphics Settings to PEG.

Ok good to know that I should use the integrated graphics when starting. For most of the tests I listed I was only using integrated graphics with the MB HDMI output on the back I/O panel. 
 
The debug LED never stops on anything - it continues cycling through numbers and letters indefinitely. 
 

I am interested in this thread as I had the same problem only my led display went straight to C and I had the memory error led on. I tried lots of different things to trouble shoot. I ended up with 2 bent pins after taking the CPU out 5+ times for pictures for Evga so when ever you do that be oh so careful (I am new builder also) I ended up getting a new z390 FTW board and hopefully this one doesn't come with the problems as we both are experiencing. (Not the best experience for a first timer learning the hobby)
 
Good luck and keep us posted!