"Iso" is a Greek prefix meaning "equal." 1C1T = 1 core, 1 thread. 2C4T is a reference to Saltwell's Hyper-Threading. What these slides show, in aggregate, is a phenomenal increase in performance, performance-per watt, and a dramatic reduction in power consumption. The benefits extend through every scenario in single and multi-threaded configurations and, according to Intel, are a key component of why Bay Trail / Avoton will decimate the competition when the new chips finally launch late this year or the beginning of next.
According to Intel, the new chips are substantially faster than anything its competitors are fielding. The company is promising dual-core Silvermont chips that are 1.4x - 2.1x faster than equivalent quad-core products from its competitors, while drawing 1.6x - 3.1x less power (The use of x-less power nomenclature is somewhat confusing).
How fair are these figures? That's a question worth asking. Intel's slides note that the "software and workloads used in performance tests have been optimized only on Intel microprocessors." On the other hand, when we first unveiled Medfield, the phone's performance and battery life tests in real world usage matched up with what Intel claimed the phone could do against the competition. In the past, Intel has been played things straight when it came to comparing its tablet and mobile phone platforms against ARM competitors, and we don't see a reason to conclude the company has deviated from that this time around.
Better performance is of limited value without better power consumption, and Intel aims for Silvermont to deliver on both counts. The "Race to Zero" has become the new 1GHz push, and Intel has further tweaked Silvermont's design to allow the chip to enter and leave wait-states more efficiently. As we've previously covered, the ability to race to minimum power consumption is extremely important to a CPU's overall power consumption.
The graphs Intel is showing at this point claim major advantages for Silvermont in this regard. Obviously, that's what we'd expect -- Intel isn't going to hand out substandard comparisons -- but take them with a grain of salt. It's not clear if these comparisons use Cortex-A15 hardware, older Cortex-A9 products built on 40nm, or both.
Silvermont will also be capable of more aggressive power budget sharing, with CPU and GPU cores adjusted on the fly to optimize performance. This is an option that's existed for multiple product generations, but Silvermont improves the cross-adjustment capability.