DPC Latency unusual. Need help

Hello there!
As I was having problems regarding stuttering with Battlefield 4 since I started playing it, I decided to run Latencymon and see if it helps me find the culprits. What I found was pretty weird. The latency was at 20us with occasional spikes to 400 that are more present during the gameplay. Sometimes but rarely, it jumps to around 1000-1500
Here is a screenshot
http://i.imgur.com/LaZTUZY.png
Maybe it is my HDD that is causing this as it is pretty old (around 4.5 years) and it's SATA. I've tried disabling virtual memory and it seems that it helps a bit fix the stuttering. Also this video shows my problem exactly: https://www.youtube.com/watch?v=c49p55OI2vY

My system:
Motherboard: Gigabyte 970A-D3 (Latest FD bios. Was thinking of downgrading, maybe it has to do something with it, what do you think?)
CPU: AMD FX-8320 @ 3.5ghz
GPU: ASUS HD7790 DirectCU II
RAM: Kingston HyperX DDR3 2x4GB @ 1600mhz (X.M.P is on)
HDD: WD 320GB SATA (To be precise: WDC WD3200AAKS-00L9A0 ATA Device; that's what it says in Device Manager. I'd set it to AHCI mode)
PSU: LC Power LC600H-12 600W
Windows 8.1 Pro x64

Any help would be greatly appreciated!

-eFeqt