FPS drops randomly

[Thanatognomonic]

Hey guys,
In a lot of competitive games I've been playing, I've been experiencing some random occurrences of FPS drop. For example, in Warframe I will randomly drop from 110FPS to a mere 15FPS for a split second.
My rig consists of: I5-4670k OC 4.2Ghz + GTX 660ti.

Personally, I put the drops down to one of two issues, HDD and broadband, though upon testing my broadband, I have roughly 35ping, 12Mb up and 1.5Mb down, so it can't be this.

I'm running two 5200RPM HDDs in my rig, could these be the problem for my FPS drops?

 

[Remixex]

Dust in the CPU Heatsink, have you cleaned it? check your temperatures with this while playing, it gives you the max temperature your CPU should be working on, and it also tells you the max temperature it reached while playing
http://www.alcpu.com/CoreTemp/

 

[Thanatognomonic]

The max my CPU seems to get after a game or two is 50 degrees.
The CPU heatsink has no dust in it, itself and the computer are only 2-3 months old, it's practically dust free.

 

[Remixex]

So there's no significant temp increase on the CPU after a significant FPS drop yes? alright try watching your GPU temps then
http://www.gputemp.com/
the HDD reduces load times, the fps drop caused by temps is noticeably different, it's very VERY choppy, irregular, and annoying, HDD might cause stutter while playing but it shouldn't be a big factor unless you have like 80 Gb of HDD Space

 

[Thanatognomonic]

I have precision X on whilst playing, so the GPU fan ramps up according to the temperature. 70 degrees and it will be running at full RPM, it never reaches this.
It is like stuttering. IT's horribly unregular, but it happens more often when more textures are loading (say multiple bullets whizzing by) or just when there's a close range gun battle going on