GPU Stuck in x8 ONLY on PCIEX16_1

[daddy_4rime]

I've recently updated BIOS to 1302 because GPU was running at x8 in the PCIEX16_1 slot. After update BIOS, GPU-Z and CPU-Z all still show that it runs PCI-E 3.0 @ x8. Running GPU-Z render test or UNIGINE benchmarks doesn't help. It still shows PCI 3.0 @ x8. Clearing CMOS, reseating GPU didn't help. Running BIOS at optimized defaults didn't help. I'm running out of options here. Important to note that I do not have anything else plugged into the PCIEX16_2 or _3 slots.

Here are my specs:

BIOS:1302
OC'ed? No.
Motherboard: Asus ROG MAXIMUS X HERO (WI-FI)
CPU: Intel Core i7-8700K
AIO: Thermaltake RIING 360 RGB
RAM: Trident G. Skill RGB 32GB (4 x 8GB) DDR4-3000
M.2_1 Slot NVMe (Boot): Samsung 960 PRO 512GB M.2-2280
M.2_2 Slot NVMe (Games): Samsung 960 EVO 1TB M.2-2280
SATA_1- Used, WD Black 1TB
SATA_2 - Used, WD Black 1TB
SATA_3 - Used, Toshiba X300 5TB
GPU: EVGA SC2 Hybrid GTX 1080 Ti 11GB
PSU: EVGA SuperNOVA P2 1000W

Thank you for your help!

[daddy_4rime]

ASUS has approved RMA for this Motherboard. Wa not able to fix the issue.

[pndiode]

I had a similar problem with my INWIN 707 computer case whenever it was moved. The VGA slots and the motherboard were not a near perfect 90 degree angle. Sometimes I had to use something other than my index finger to release the graphics card.