Motherboard no longer properly detecting m.2 sata ssd

[ShadyHamster]

Hi guys, thanks for checking out my thread.

So my issue just started happening today after getting this system to a workable state.
This system has been sitting around for quite a few months and everything was working fine up until now.
While the ssd is connected, POST and booting in to windows is quite slow.
The ssd works in other systems and other sata based m.2 drives work in the motherboard, the ssd works and is detected fine when installed in a usb m.2 enclosure.
Other things i've tried are updating the motherboards bios and updating the ssds firmware, both didn't help.
The motherboard is an Asus Maximus X Apex
The ssd is a Crucial MX500 1TB M.2 drive

Other hardware:
8700k
GTX 1070 Ti
16gb G.Skill 3200Mhz Trident Z RGB
Samsung 970 EVO 500GB
Corsair AX760 PSU

As soon as the ssd is connected to the motherboard the built-in activity led lights up and remains lit until the drive or power is disconnected from the system.

I've been at this for a few hours now trying everything i can think of, short of disassembling the entire system, this would require a watercooling loop drain and dismantle.

So if anyone has any ideas for what to try next i'm all ears.

 

[ShadyHamster]

Alright, nvm, i figured it out.
Turns out it was the Display Port cable, yes you read that right, it was the DP cable.
Can someone explain that? How does a cable running from the graphics card to monitor effect an ssd.