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.
- Did You Know Mobile Haswell Doesn't Support 1.5 V DDR3?
- Ripjaws DDR3-1866 Low Voltage
- Ripjaws DDR3-1600 Low Voltage
- G.Skill Standard DDR3-1333
- Test Hardware And Software Configurations
- Results: SiSoftware Sandra
- Results: 3DMark
- Results: 3D Games
- Results: Adobe Creative Suite
- Results: File Compression
- Power, Efficiency, And Final Thoughts
The R version has 128MB of L4 cache. At 1280x720, it is large enough for all index and vertex buffers and most textures. That is why main memory speed doesn't significantly affect Iris Pro 5200...
intel claims that the edram costs around $80. that'd jack the a10 6800k price over $200 only to benefit the igpu (possibly the same with gddr5). imo, the weaker cpu cores wouldn't benefit much, if at all. that'd make the apus of poor value and people will argue against the apus claiming you can have a faster configuration under $200 (e.g. core i3 4110/fx6300 + radeon 7770/7750) without requiring the edram. as for core i7 4770R (and other R skus) - it's way too expensive. afaik, brix pro is barebones, the whole pc might cost near $800-1000 fully configured.
Simply wait for Broadwell-K near the end of this year and you will get the option of buying a $300+ i5 or $400+ i7 with 128MB L4 cache and Iris Pro.
From what little info leaked about it so far, it is still unclear whether or not there will be an option to buy a desktop Broadwell without that ~$100 extra.