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never heard about Crystalwell?
We know about Haswell’s massive shader count, and we know why it has them, but what is Crystalwell exactly? The answer is simple, really wide DRAM on the package, not that fast, but more than wide enough to make up for it.
SemiAccurate’s sources are now saying that Crystalwell bearing Haswell GT3s use a DRAM variant, likely DDR3 or LP-DDR3, for their memory. That memory, referred to eDRAM, although not in the classic sense of, “IBM can’t fab that chip at economically viable yields because they use….” type eDRAM, it is not on the same die. Crystalwell puts custom designed DRAM on an interposer with a 512-bit wide data path to the CPU/APU.
In mobile applications, batteries are sensitive to peak current demands of electronics, as noted in two recent industry articles (one in EE Times by Energizer and an app note from TI). You can get about 50% increased battery life by reducing repetitive peak current demands. Here is a technology that helps reduce IC peak current, InnovaClockControl, http://www.innovaclockcontrol.com/low_power_vlsi_design.html.
Yes - it's really important for Intel followers to realize that while Intel's performance/power gains are staggering for Intel, a Haswell core still uses about 7 watts, compared to an entire iPad 4, which uses 4 watts, most of which powers the screen. It's Intel's performance numbers at a half watt that will matter.