Sudden stuttering ingame despite having high FPS?

Okay, I am a gaming enthusiast. At the moment I have 10 games installed, one of which I have invested over 700$ in, called Rift. Rift up until two weeks ago was running completely fine, smooth as butter. But for some extremely odd reason it began stuttering, despite having 60+ FPS (Frames Per Second). Disabling SuperSampling (AntiAliasing) removes 80% of the stuttering. But please keep in mind that even with SuperSampling enabled my FPS is 60+ and never dips even during this stuttering. And this problem has just appeared out of no where. Something isn't right. I am thinking my problem may be related to my hardware, a physical problem even though my other games run fine. Here is a list of the trouble shooting steps that I've taken so far.

1. Running the game on ultra low setting, there is still strong signs of this stuttering
2. Disabled my Anti-Virus and Anti-Malware
3. Uninstalled the game thoroughly and reinstalled
4. Scanning for malware & viruses using multiple top programs
5. Reformatted my hard drive
6. Replaced thermal compound on CPU & GPU even though temperatures were fine
7. Reseated my ram
8. Tried another Power Supply Unit
9. Tried another GPU but the GPU used was very old so I can not rule out the GPU
10. Ran all the internet connection tests that I could, internet connection is fantastic
11. Connected my ethernet cable directly to the modem.
12. Updated my Gigabyte BiOS
13. Disabled Hyper-Threading
14. Verified all hardware is configured for MAXIMUM PERFORMANCE
15. Unparked my CPU
16. Trying the game on another PC of almost equal performance I was surprised to see what I believe was the same issue, not as bad, but stuttering nonetheless, I could not get a FPS count on this PC, but I just don't believe it is having the same issue I am, unless there is something wrong with my modem, but if there was a problem with the modem I would imagine the connection tests I had performed would not have all passed, and I would be suffering from some kind of packet loss which I am not.

Here are my system specifications:

Intel Core i7 Quad
16 Gigs of "XMS" RAM
Western Digital 2 TB Hard Drive Black Series
EVGA nVidia GTX 760
Gigabyte Motherboard (Nothing to Special)
Antec 500w PSU (PC Requires 430w)
ASUS Blue Ray

Rift is one game I do not need VSync, I have attempted already to overclock my GPU with software such as Afterburner to no avail, if that is what you mean. And Rivatuner I can never figure out, but I will download it and give that a shot if I can figure it out and I'll get back to you.