z370 HD3: Not detecting GTX 1080 in PCI-e 16 slot + RAM issues

[galimird]

Hello guys,

Really hope you have some advice. I rebuilt my desktop yesterday with the following (main) parts:
Motherboard: Gigabyte z370 HD3
CPU: Intel i5 8600k (Coffee Lake)
GPU: Gigabyte nVidia GTX 1080
RAM: Corsair Vengeance LPX 3000mhz DDR4 - 2x 8 GB
Harddrives: 3 SSDs

It was a bit of a nightmare because the GPU was not detected until we put it in the PCI-e 4 slot - which is obviously not optimal. Additionally the RAM would prevent the machine from running until we installed either 1 block in slot 1 or 2 blocks in slots 1 and 2. The motherboard and CPU are supposed to support dual-channel memory which normally requires the blocks to be installed in either slots 1 and 3 or slots 2 and 4. (from the motherboard manual)

What I've tried already:
For the GPU:
- Updating the bios to the latest version
- updating the GPU drivers
- resetting the bios
- putting it in the PCI-e 4 slot (which detected it proving the GPU is fine)

For the RAM:
- all possible configurations with the 4 slots and 2 blocks

Any advice would be greatly appreciated!

[shadowsports]

Greetings,
So you are running F4 and the card does not work in the x16 slot?  What PSU do you have and do you have the card connected to aux power correctly?

Try removing the card and loading set up defaults in BIOS.  F10, save and turn off, then install the card into the x16 slot.  Do not make any significant changes to BIOS settings while troubleshooting.

Memory issue:
Most are running 3200Mhz memory with this chipset / CPU combo.  The sweet spot for the CPU is 2666, Timings are
15-17-17-35, 1.35v. 

You may also want to confirm if the kit you have chosen is on the QVL for your board:

http://download.gigabyte.us/FileList/Memory/mb_memory_z370-hd3.pdf

Try using XMP Profile 1 or 2. Please see page 24 of your manual

Do not make a bunch of changes while troubleshooting.  You don't need Fast Boot, etc. 

F10 to save again and test restart.  If it doesn't work, you'll have to try setting memory timings and voltage manually in M.I.T.  Just use 1 DIMM installed in slot 1 or 2 while you make these settings.  F10 to save, turn off, then move the DIMMs back to what's recommended for dual channel operation.  Slots 1~3 or 2~4.  Don't move the DIMMs until you have one stick properly detected and running at 3000.