PC/Monitor/GPU Being Weird

[Lythrilux]

I turned on my machine this evening to find that my primary 1080p 144hz monitor could not detect an input via DisplayPort. I use a second 60hz 1080p monitor in portrait on my left.

• Everything was working fine yesterday
  
• Yesterday I changed the PCI slot my GPU was in to improve airflow (it was in 4, moved it to 1). It was running fine without issues before and after this.
  
• When plugged in via DisplayPort there is no incoming source from my GPU. The monitor turns on repeatedly only to inform me there is no input.
  
• When plugged in via DisplayPort, in my Windows 10 display settings the monitor is there however my settings are locked to display only on my 60hz monitor, and I cannot extend the displays.
  
• Both monitors display as 'Generic PnP Monitors'. I can't remember if they actually had branded entries before. They're ASUS monitors.
  
• I've moved the graphics card between PCI slots again and this hasn't fixed it.
  
• Whilst DisplayPort cables do not work (I have tried two, both are sufficient enough to output at 144hz) however HDMI cables and a DVI cable, with a DisplayPort Adapater going into my GPU, work to some extent - they are locked to 60Hz.
  
• I have reinstalled my drivers several times, two clean reinstalls.
  
• Previously I couldn't shift from 60hz at all, I'm somehow able to at least downgrade to 50Hz on my main monitor.
  
• I couldn't output to 4k in either monitor previously, but I've somehow got that working again.
  
• Graphically intensive applications seem to run just fine other than being stuck at 60hz.
  
• I can't see any hardware setting on the monitor relating to refresh rate.
  

GPU: Gigabyte Windforce RTX 2070 8GB
Monitor: ASUS VG248QE

I've checked Google and can only find problems that are loosely/vaguely similar to this but they don't really help. Please advise.

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