Not really, the best greases for ram are non-conductive greases. Céramique was a popular choice, but it has been a while since I checked the cooling performance of thermal compounds. The real performance from applying thermal grease to RAM would be very negligible since newer CPU's have a bigger L2 and L1 caches. Pretty much all mid to high end RAM will have a heat spreader and factory applied thermal compound. Overclocking RAM will give you better synthetics, but not by a significant amount.