Gaming stuttering issue

[ExTReMMe98]

Hello, guys, I begin by saying that this is my very first post on your site, which I find to be most helpful, due to its containing valuable information about various PC matters.
So, to get straight to the point, this is my pc's configuration : an Inter Tech SL700A PSU (with an electrical power of 700 W), Intel Core i5 4460 3.2 GHz, 16gb ram (2x8 Kingston HyperX. Savage 1600 MHz), along with a Gigabyte Geforce GTX 960 Windforce 2x OC, having 4 gb of video memory; the computer is connected to an LG monitor, whose max resolution is 1366x768, at a 60 Hz refresh rate.
The technical issue I'm facing is determined by a certain sttuter (with a small fps drop from 60 to 52-55 fps, but it's quite noticeable and annoying) in games which contain fast-moving images like GTA V (the stutter occurs only while driving) or The Crew Wild Run, but it's completely absent from FPS games (like Rainbow Six Siege or Blac Ops 3).
I use Vsync in order to eliminate the disturbing effect of screen tearing, locking my game fps at 60 fps. However, I don't think the stutter is due to this setting, for I tried to run the two above-mentioned games without it, and it still stuttered a bit in some places, not to mention the horrible sreen tearing, although the frame rate maintained a constant 70-80 fps.
Here's what I tried (none of the following managed to fix the issue completely, but I can not say that changing the Nvidia Control Panel settings didn't improve things in some way) :
1-Reducing the video settings to lowest values;
2-Using my Samsung LCD TV as a video source, to see if maybe my monitor might have been the cause of the problem;
3-Changing the Nvidia Control Panel settings in order to squeeze every single bit of performance out of the video card ( like for e.g. activating Triple Buffering, High Performance Mode, Single Display Compatibility mode etc.);
4-Turning on my computer with the side case open, thinking that maybe the GPU'a temperature might have overheated during gameplay, even thought the FAN's kept normal rpm's, without producing any strange noises.
5-Using Nvidia Control Panel's DSR (Dynamic Super Resolution) option at a "2.00x (native resolution)" rate, because I considered that perhaps the issues was caused by my monitor's resolution being too low for the GPU (even though it wasn't logical at all).
6-Updating, downgrading and then re-updating my video card's drivers.
Finally, my view on the whole matter is that the stutter issue is mostly caused by my HDD's being almost 6 years old, a Seagate Barracuda with 500 gb storage space and 7200 rpm, and so its read and write speeds aren't fast enough for loading all these detailed textures, especially on high/very high graphics settings.
Given to this view of mine, I made a test while playing GTA V Online in a very populated public session.
I minimised the game, opened Task Manager, selected "Performnace" tab, and both the "Read" and "Write" speeds of the hard disk were situated in the range of 100-600 kbs/sec (not even 1 MB !!! ), although the hard-drive consuming status didn't exceed 7-10 %.
As for the CPU and RAM consuming percentage, there was nothing abmormal at all : the game was taking 50-60% of the CPU and no more than 6-7 GB of the RAM memory.
Most of my friends suggest I quickly buy an SSD, a Samsung EVO 840 (don't know yet if I will choose the 250gb or 500gb version), as it will not only speed up every possible aspect of my system, but also solve this performance issue, which should have never existed, considering the specs of my pc.
In conclusion, I hope you can offer me some advice if my final guess was right, and thank you anticipated for your support !

 

[Spencer_10]

Hello,
First thing to check, is your Ram installed correctly and running in Dual Mode?

2. Does turning on / off Vsync make any difference?

3) Yes it could well be the hard drive, especially in a game like GTA, benchmark it and see how bad you 4k read/writes are.

 

[ExTReMMe98]

Yep, checked that already in my BIOS, they're running in "Dual Channel mode". Plus, let's think about this straight : if the RAM modules weren't installed correctly, my system wouldn't be able to boot properly, maybe even at all.
But could the fact that my video card's bus is 128bit be the cause of the issue ?
I tried to run the game with Vsync completely turned off, the fps jumped to 70-80, even 90 in some places, but, besides the annoying screen tearing effect, the stutter could still be felt in some places.
How should I benchmark GTA V ? If I use the in-game benchmark utility, there's nothing strange at all, the game runs with a constant 60 fps (barely dropping by 1-2 frames), even on ultra settings.

 

[Spencer_10]

Thats good, it will boot if ram sticks are in wrong slots but uses single channel mode.

No I mean benchmark the hard drive using Crystal disk mark or AS SSD benchmark

 

[Spencer_10]

Another thing to try, Sometimes HDMI can cause odd stutters on some screens... try DVI if you can or VGA.

What are your CPU and GPU temps before and during gaming after 5-10 mins?

 

[ExTReMMe98]

I only have two slots of RAM on my motherboard, so there's no way I could install them incorrectly (at least that's what I think, correct me if I'm wrong).I strongly consider my HDD is the main factor causing the stutter, as it's the oldest component in my entire system which hasn't yet been replaced. I've also taken a look at Geforce's website, where they described that the main cause for stutter lag is an old HDD, like mine is.

 

[ExTReMMe98]

I've been using VGA (with an adapter to DVI) for two months, since I have this video card, so that's not the cause. I'm gonna try one of the programs you suggested for analysing my disk.
My GPU temperature, which I already thought of checking, doesn't go beyond 48-50 degrees Celsius in gaming.

 

[ExTReMMe98]

I've taken a picture of my "M.I.T Status", from the BIOS menu, and I'm going to attach it below, so that you can have a look and tell me if there's something wrong with those parameters, like for example if dual channel memory mode is disabled.