Yes you will see synthetic memory benchmarks like everest and sandra improve, and a small improvement on spi 32m. But on testing real world apps, games, etc very little, if any difference. If your memory is rated 1600mhz 7,7,7 24 at 1.9v that may be your problem. Did you not get i7 rated memory or is that a typo? memtest is not an accurate gauge of memory stability on i7 presumably because of the integrated mem controller. Many including myself can run memtest all day (hours and hours) without an error, but can not get linpack max memory stable on i7 using same settings without increasing mem volts.

But I would try 1.35 volts qpi first, if that fails I would try bumping up mem volts as that may be the problem. Will be interesting to see the results if your mem is rated at 1.9v.