I'd avoid suggesting liquid metal thermal pastes to people who don't seem like they have the experience to re-paste on their own initiative. Given how difficult it is to handle, and the risk of killing hardware (
especially given the massive amount of surface-mount components immediately surrounding the 380X die!), I'd advise against it. That card has to be 2-3 years old, chances are it could do with a re-pasting anyhow, and most OEMs use cheap thermal paste that dries out over time. Thermal Grizzly Cryonaut or Gelid GC-Extreme should be perfectly fine, not to mention entirely safe no matter how it's applied.
@Micky12345 : from your post, it sounds like you removed the cooler and reattached it without replacing the thermal paste? Generally, that's a bad idea, especially on a card where the paste is old enough to have dried out. Then again, it doesn't sound like it could have gotten much worse from what you're saying, but that definitely doesn't help. Get some rubbing alcohol and paper towels, carefully rub off the paste from the die (avoid touching the tiny components around it as much as possible - they
can snap off and brick your card), add a blob (amount really doesn't matter for GPUs, just don't use too little - rice grain size is fine) of one of the pastes mentioned above, and you should be fine. Of course, while you're at it, remove any and all dust from your heatsink and fans. If the heatsink is especially dusty, free it from the shroud and fans and rinse it in warm water and let dry. Fans are best cleaned with a damp cloth or something similar that's easier to get into the tiny nooks and crannies around the blades.
If this doesn't fix the issue, chances are something in your GPU is degrading (has it been OC'd?), and it's likely on the verge of failure. That's rare, though, as GPU failures tend to be rather immediate.