Case fan Solution

[gunrage]

Hello friends. I've been watching Linus tech tips for over a year now but I've never tuned in to these forums.
So lets get to my problem. My current case is Cooler Master Elite 430 (My side panel has 2 fan slots and no window). I have a front and rear 120mm fans. And I'm buying a third fan.
I've heard from our fellow Linus that higher inside pressure must be maintained so that less dust goes in. 
My question here is where should place the third fan If I'm aiming mainly for better VRAM and RAM cooling. 
My current plan is to place it as an intake fan either on the bottom or the side hole blowing directly at the graphic's card.
I noticed I have a slight cooling problem when I started playing GTA 5 which uses almost all my current 8gb. (upgrading to 16GB along with the fan)
After some time playing my sort of old setup (mentioned below) starts to stutter and rubberband in game. And looking at the temps I think it might be a Temp issue.
My GPU cant ever go above 61°. My Vram however goes to 70+ and that might be the main issue. 
I tried to see what the RAM temps are but I don't think I have sensors on it. Nothing comes up in AIDA 64. 
I Started using a custom fan curve in Asus Gpu tweak which lowered my Overal temps by 7-10 degrees but that only delays the ingame problem.
None of my components are overclocked.

 

Setup: Motherboard   Asrock B75 Pro-3M

           Cpu                 i5-3570 @3.4Ghz

           Gpu                 Asus Gtx 660 2GB Vram

           RAM                2x4gb ADATA 1600mhz (soon to be 4x4GB)

           SSD                 Samsung 840Evo 250 GB

           HDD                Seagate Barracuda 1TB 

           PSU                 Seasonic SS-620GB 620W (80 plus Bronze) Non modular

I'm sorry for the long post. If anyone has a better Idea what my problem could be or a better cooling solution I'll be glad to try it out.

 

[blackadder]

I dont think vram cares untill it gets to like 80c or more. I would still put the fan by the gpu if you want, the side panel. Are you getting crashes or thermal throttling?

[LogicalDrm]

Might not be problem in overheating at all but more with GPU running out of VRAM. But to the point of placement. I would suggest using side mount since bottom could be blocked by cables from PSU.

[gunrage]

Thanks for the sugestions. 
I'm using the Geforce Experience recommended settings which require way more Vram then my GPU has. Although according to GPU tweak the memory usage never goes above 1500-1600 mb

Edit: Could it be a lack of ram issue because with nothing else on besides steam and GTA it goes up to 7.5/8 GB