Question Computer randomly posting with GPU, suspected PSU issue?

[SHORTCIRCUT]

I’ve been using my computer for a while and barring some software problems, it ran more or less fine when I’ve used it. Eventually I ran into some issues where games would immediately cause the PC to crash with a black screen, in which after some investigation and some assistance from others, it was determined to be because the GPU wasn’t inserted correctly. Mistake fixed, no big deal


Now I’ve come across another issue. My PC is barely even POSTing nowadays with the GPU installed (it can still boot and fans spin etc etc.). When I take out my current gpu and swap it with my previous 1070ti, everything works fine though. At first I thought it was due to GPU sag, as when I propped it up it seemed to fix all the issues momentarily. But after some long trial and error, it turns out to be an issue with the pci connectors from the psu.

Here’s the main issue. If I tinker with the cables a bit (nothing specific, just random shifting around) I can get the pc to POST and everything works perfectly fine, gaming and all. However, it only works for that initial boot and after shutting down, I have to redo the tinkering just to get it posting again. My assumption is something wrong with the PSU but at the same time there are reasons I don’t assume so. Like for starters it works fine with any other gpu, and when it does end up working, it works perfectly fine with my current gpu. Or how only a few weeks ago it was at least posting regularly instead of not being able to post at all. But at the same time I’m no expert so I could be completely wrong with my assumptions. I want to try switching the pci cable, but I’m afraid of taking out other components (as its hard to take the cable out of the actual psu atm) in lieu of damagin them


Specs:

Specs:

CPU: Intel® Core™ Processor i7-9700KF 3.60GHZ 12MB Intel Smart Cache LGA1151 [w/o Integrated Graphic] (Coffee Lake)
1TB WD Blue Series SATA-III 6 GB/s SSD (Plus 16GB Intel Optane Memory SSD Acceleration 2X Faster)
1TB WD Green Series SATA-III 6 Gb/s SSD
A 2TB Hard Drive from my previous computer that I installed into this one
MOTHERBOARD: ASUS Prime Z390-P ATX w/ WiFi 802.11AC RGB, USB 3.1, 2 PCIe x16, 4 PCIe x1, 4 SATA3, 2 M.2 SATA/PCIe
PSU: 750 Watts - Thermaltake Toughpower Grand RGB 750W 80 PLUS GOLD Certified Full Modular
GPU: EVGA GeForce® RTX 2070 SUPER™ XC GAMING 8G GDDR6 (Turing) [Old GPU used was Zotac 1070ti Mini]
RAM: 16GB (8GBx2) DDR4/3000MHz Dual Channel Memory (GSKILL Trident Z RGB)

I only just noticed now how Thermalttake isn’t exactly the best choices according to the sticky, so I really do hope that it doesn’t turn out to be the issue. I’m honestly at a loss at this point, any help would be greatly appreciated.

 

[SHORTCIRCUT]

Ok so a few changes have happened since that last post.

I somehow managed to sneak in another pci cable into the PSU, and tried it with the GPU. No fix. I tried various combinations between both wires yet nothing came about.

Also tried cleaning the pins on the gpu using a pink eraser (as they were quite dirty). While the pins aren't super clean they're at least a lot cleaner than before. No work

One other thing that might be of influence, is that I noticed even if I don't connect the psu cables at all the computer still won't POST (the card's fans/lights still turn on b/c of pci power I assume?). When I tested it with my 1070ti without connecting the PSU cables, at the very least the computer would still POST, so I'm not sure how relevant that info is. Unfortunately I didn't test that no psu connection at a time when I knew the current GPU was working

Is is still too early to write off the GPU as not working, or is there anything else I can try?