Is my memory bottle necking game performance?

[Riggadan]

I recently built a pc.

Specs:
i5 3550 @3.3ghz
HD 7850
4gb 1333mhz ram
Win 7 Home Premium 64

It runs BF3, Dirt 3, Skyrim, and most new titles at 40+fps max settings 1080p. However i'm running into problems in GTA 4. I have the ice enhancer graphics mod installed, and on 1080p and medium settings, I can barely manage 30fps. The strange thing is, i get the same frame rate at 720p and all other resolutions. I think my 4gb ram is holding back my system, since GTA 4 uses 2.5gb in task manager, and Win 7 uses 2gb. I have a 2gb ram stick coming in the mail soon, so do you guys think that will help me boost my framerate in GTA?

P.S. all drivers are up to date, gpu is overclocked to 1050mhz from 860mhz core clock

 

[EarthDog]

I highly doubt it. Metro 2033 brings ALL GPU's to their knees. Im a bit concerned at the statement of you ordering ONE stick of ram (I would assume to total 3 sticks). You have a dual channel system there and using 3 sticks will cut that one stick back to single channel I believe.

You best bet is to just buy 2x4GB as they are really cheap right now.