HDD maxed out

[ziogref]

Before I start, I know Software raid is bad, but to buy a Dedicated card is WAY to EXPENSIVE for what i'm using my home server for. So when Im downloading a torrent, It tends to max out my 100mbit fibre connection, However uTorrent stops responding, recovers, stop responding, recovers looping until the torrent is seeding. When this is happening ram is NOT maxing out, still has around 1-2gb left over (im running a few other other things, they run of the SSD) My raid 5 that the torrent is writing to seems to be maxed out in Performance manager. So im wondering if there is some sort of fix or will I have to purchase something (Cache disk maybe?) Specs and setup below

 

I am running the latest version of uTorrent

I Have about 350-400 torrents in utorrent from private trackers (note: they only actively seed for a few days and then mostly sit inactive for 4 months before it utorrent Stops them) then I have a script that runs that moves the files from my raid 5 to my raid 1 to archive, extracting any rar's and then deleting the rar files.

 

ASUS Z97I-PLUS Motherboard

Intel Core i5 4690

Thermaltake 650W Toughpower Gold

Kingston Hyper X Fury HX318C10FBK2/8 8GB (2x4GB) Black

2x8tb raid 1 (Software Raid)

4x2tb Raid 5 (Using a host card) (Software Raid)

4-5 year old Corsair 120gb Boot drive

Windows Server 2012r2 Standard Edition