Hey there, @TSP1337!
I'd strongly recommend you backup all the data from that particular SSD somewhere off-site (e.g. external storage, cloud storage, etc.). This is how you will avoid any potential data loss, in case there's really something wrong with the SSD. After making sure your data is safe, try running the SSD's brand-specific tool or a third-party diagnostic utility to determine what is the health and SMART status. I'd also strongly recommend you try using a different SATA cable and SATA port when you connect that SSD to the mobo. A failed connection could just as easily be causing the spikes and poor performance (transfer rate). I'd second @dudeman's suggestion about checking if the SSD is properly configured in AHCI mode from the BIOS.
If you have access to another working PC, you could also try plugging the SSD there as well and track how it will behave in the other system. If the SSD is still covered by its warranty, you should definitely consider RMA-ing it and getting a replacement from the reseller's / manufacturer's customer support.
Hope this was helpful. Keep us posted if you have more questions.
SuperSoph_WD