The following tests were conducted to see how much difference a RAM (memory) really makes in gaming.
Our test system was ASRock Extreme 4 Motherboard with an i7-4770 and a GTX660.
We started with 8 gig of RAM then doubled it to 16gigs and then doubled it again to 32 gigs.The benchmark program we used was 3Dmark11 as it is a 64bit program (Other benchmarks are only 32bit and therefore do not utilise the full amount of RAM)
The test system with
8 Gigs of RAM : 6709 3DMark11
16 Gigs of RAM : 6731 3DMark11 (a performance increase of 0.0032%)
32 Gigs of RAM : 6741 3DMark11 (a performance increase of 0.0047% from 8gigs)
As you can clearly see extra RAM in gaming does very little. We always recommend 8gig of RAM for gaming.
Upgrading the graphics card will enhance performance for gaming and upgrading the CPU will speed up the system even more in general usage.
Please bear in mind that the graphics card does about 90-95% of the work in gaming.
Extra RAM will help in keeping multiple windows open at the same time and certain programs also benefit from more RAM like large files in Adobe Photoshop.
Adding a lot more RAM will not benefit gaming.