Power, Efficiency, And Final Thoughts
Continuous testing showed a one to four watt difference between 1.50 and 1.35 volt memory settings. This difference remained consistent through all speeds, though it’s only shown for the latency-optimized setting. Data rate appears to have a larger effect on memory power consumption, but only when the RAM is loaded and unloaded at unrealistic capacity levels.
We were hoping that the Core i7-4770K could realistically represent the BGA-based Core i7-4770R at both voltage levels, but that’s just not the situation. The LGA 1150-based CPU enjoys a performance jump averaging 17% in the transition from DDR3-1333 to DDR3-1866. The same data rate increase only affected the Core i7-4770R by a mere 4%.
You may have noticed that we have two baselines in the charts. That's an important fact, particularly when you look at the efficiency calculations. Both platforms compare the efficiency of DDR3-1866 and DDR3-1600 results to their own DDR3-1333 baseline.
The embedded platform with Intel's Core i7-4770R becomes 2.4% more efficient at DDR3-1600, but a jump in power demand drops its DDR3-1866 result to sub-baseline levels. The socketed Core i7-4770K also enjoys its highest efficiency at DDR3-1600, but stepping up to DDR3-1866 helps performance enough to partly offset increased power consumption.
Our performance data tells us that the best market for fast SO-DIMMs is likely compact machines with LGA 1150-based CPUs, even though the memory form factor is more specifically intended for notebooks, many of which instead employ low-voltage processors soldered down. Power measurements further specify that low-latency DDR3-1600 is the best memory for our specific Core i7-4770R-based platform.
Switching our attention over to graphics performance, it was more startling to compare HD Graphics 4600 to Iris Pro graphics 5200 than it was to gather the memory-oriented benchmarks, warranting further exploration. It'll be more difficult to explain why the -4770R saw so much less benefit from higher data rates than the -4770K. Further testing of the embedded system would require me to acquire a Core i7-4930MX model that’s otherwise identically equipped.