gta 5 stuttering problem

Hello, Im experiencing this problem with gta 5 stuttering, the game runs at 60 fps but as soon as it drops by just 5 fps it stutters(micro-freezes) and sometimes freezes for 1-2 seconds. I run everything on high, although it stutters just the same on normal settings. Anyways what Im trying to find out is what is causing the problem and what should i upgrade to make it run smoothly, I think it could be the ram or maybe the power supply? On high settings the game takes about 70%-80% of my gpu, 40%-80% of my cpu and 5500MB to 6700MB of my physical memory leaving only about 1500MB available. Also when it stutters none of those rise just the fps drops to about 55 sometimes it stays at 60fps and still stutters. Sorry for explaining this problem in such a confusing way but Im not really good with computers and I'll be thankful for your replies.

This are my specs
Processor (CPU) Intel® Core™i7 Quad Core Processor i7-3770K (3.5GHz) 8MB Cache
Case NZXT PHANTOM WHITE GAMING CASE
Motherboard ASUS® P8Z77-M: MICRO-ATX, USB 3.0, SATA 6GBs, ATI®CrossFireX
Memory (RAM) 8GB KINGSTON HYPER-X GENESIS DUAL-DDR3 1600MHz, X.M.P (2 x 4GB KIT)
Graphics Card 2GB NVIDIA GEFORCE GTX 660 Ti - 2 DVI, HDMI, DP - 3D Vision Ready
1st Hard Disk 1TB 3.5" SATA-III 6GB/s HDD 7200RPM 32MB CACHE
1st DVD/BLU-RAY Drive 24x DUAL LAYER DVD WRITER ±R/±RW/RAM
Power Supply 450W Quiet 80 PLUS Dual Rail PSU + 120mm Case Fan
Processor Cooling INTEL SOCKET LGA1155 STANDARD CPU COOLER
Sound Card ONBOARD 6 CHANNEL (5.1) HIGH DEF AUDIO (AS STANDARD)
Wireless/Wired Networking 10/100/1000 GIGABIT LAN PORT - AS STANDARD ON ALL PCs
USB Options 6 x USB 2.0 PORTS @ BACK PANEL (MIN 2 FRONT PORTS) AS STANDARD
Operating System Genuine Windows 7 Home Premium 64 Bit w/SP1 - inc DVD & Licence
Monitor IIYAMA E2773HDS-GB1 27" LED WIDESCREEN, HDMI/DVI-D HD1920x1080

Hello Adamm,

I would start with lowering all your settings to the lowest possible, and running the game for a little to see if the stutter is still present. Leave the resolution at 1080 if that's what your playing.

If you find that the stutter is gone start cranking up the settings until you find a balance that you like between looks and performance. Use the Advanced graphics last as these will eat up your FPS.

Also make sure that in the POWER SETTING within CONTROL PANEL you have the rig set to high performance instead of balanced this also helped me out a bit.

Hope this helps, let us know how you get on.

Things you can try in order to eliminate stutter:
1) Make sure shader cache is enabled in NVIDIA control panel.
2) Once the game has loaded Alt tab out of the game and bring it back up.