Calvindude22 :
I have an AMD card so there is no adaptive vsync option only either on or off. The drops in fps dont happen right away either, they tend to happen mid way through and then it just doesnt go back up
Ok so thats good and bad news, the good news are that we know it's not a software/drivers issue, the bad news is that that's a hardware issue.
You said that the GPU and CPU temps are good while been under load, so it leaves us with three possible scenarios:
1. The GPU/CPU is slowing itself down to prevent any damage to itself.
2. The PSU can't comply with the amount of Watt needed or failing to do so for various reasons.
3. Less likely bot possible, your mother board is failing to deliver enough power to the GPU/CPU.
There may be other reasons but those are the main ones.
So the next step is finding the problematic part:
* Find a PSU, preferred a 500W and above and play something, look for any drops.
* Finding another GPU and play on it for a while (preferred a good one so it'll have the same power consumption), see if the drops occur again.
* This one is easier - put your GPU into another PC, install the AMD drivers on that PC and play some intensive games, if the drops reappear - 99% a faulty GPU.
Hopefully this will be it.. I would really like an update on that, Good luck!