Non replicable boot issue

[FL630]

Hi OCUK members,

First time I've had a proper boot issue and I'm thoroughly stumped.

PC spec as below:
i5-8600k (OC 5.0GHz rock steady)
Asus ROG Strix Z370F
Corsair Vengeance LED DDR4-3200 16Gb (2x8)
Asus Strix GTX980 (Stable OC of over 2 years...)
EVGA Supernova 750 G2 PSU.
Custom WC loop

You can see the build here: https://forums.overclockers.co.uk/threads/upscaling.18798375/


The problem I am having is a BOOT issue, or even a POST issue. I have spent the last half an hour trying all configs of RAM in the motherboard as I think the problem lies here. In the past I've removed the DIMMs in the hope I'll find what's faulty, only for it to fix itself, then get worse again.

So I've tried the following (slot 1 being on the right, 4 being left):

Stick 1

Slot 1: No Post
Slot 2: No Post, no video output from GPU.
Slot 3: Slow post to BIOS, restart to W10 fine, restart 2 fine, 3 fine, 4 fine.
Slot 4: 4x Fast post and load into Windoze
​

Stick 2

Slot 1: No post, second try slow posted to bios, started fine on restarts
Slot 2: Works fine
Slot 3: Works fine
Slot 4: Works fine
​

Stick 1 Slot 1, Stick 2 Slot 3 (recommended in manual): Slow initial boot, then subsequent restarts fine

Stick 1 Slot 2, Stick 2 Slot 4: Worked fine

Stick 1 Slot 3, Stick 2 Slot 1: Worked fine

Stick 1 Slot 4, Stick 2 Slot 2: Working fine

Memtest comes back clean on RAM.

Again, if I go to start on anther day it might freeze at the "Press F10 or DEL to enter BIOS" screen, somtimes it passes that and fails to get the spinning dots on the following screen before it loads into W10.

Any ideas where to go from here?

 

[Seal2fast]

it sticks serial number try using the lowest number in slot 2 and the other in slot four

also dose ur mb have memok button

another thing wot was it voltages for it oc

and wot did u use to oc ram xmp or manul

possible ur timmings to tight if u configure manual

vccio and system agent voltage cud be wrong too