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Evolution or Revolution?
23 September, 2009 in CPU
Code-named "Calpella", the Intel® Core™ Mobile i7 processors will dramatically overhaul what you expect from mobile processors.
There may be some sticker shock from looking at the higher price tags on what appear at first glance to be much slower processors (the low-end Intel® Core™ i7-720QM is 1.6~2.8 GHz, while the high-end Intel® Core™ i7-920XM is 2.0~3.2 GHz). However all of these new processors have 4 Hyper-Threaded cores (4 cores, 8 threads). This together with Quick Path Interconnect (QPI), which moves away from the Northbridge memory architecture to an on-chip memory controller, make these processors significantly faster than their clock speed might indicate. As AMD said years ago, clock speed isn't everything. AMD may have said it, but Intel finally proved it.
Early benchmarks have pitted the mid-range Intel® Core™ i7-820QM (1.73~3.06 GHz) in an otherwise unremarkable system (4GB DDR3 memory and an nVIDIA GeForce GT 240M) against the Intel® Core™2 Quad mobile powerhouse QX9300 Extreme processor in a very high-end system (8GB DDR3 memory and an nVIDIA Quadro FX 3700M). In every test but one, the Intel® Core™ i7-820QM outperformed the Intel® Core™2 Quad QX9300 Extreme processor with the higher clockspeed (and in the one test where the QX9300 won out, the extra RAM was what made the difference, not the processor). Given equal specs, the Intel® Core™ i7 processors with lower clock speeds absolutely devastated the previous-generation Intel® Core™ 2 Duo and Quad systems. The same tests also put an Intel® Core™2 Quad Q9000 with 4GB of DDR3 RAM into the mix, which lagged far behind the Intel® Core™ i7-820QM.
One of the new technologies that allows the Intel® Core™ Mobile i7 architecture to so thoroughly trounce its predecessors is Intel's new Turbo Boost technology. Up until now, we have tended to only recommend Intel® Quad processors to people using software that can take full advantage of all four cores, because software that can not use all four cores benefits much more dramatically from total clock speed than it does from a couple of extra cores. The new Intel® Turbo Boost technology constantly monitors all four cores. If it sees that a single core is being pushed to the limit, while the other three cores are hardly being used at all, it will dynamically shut down the other cores and apply their power to overclock the core in use. In real-world terms, Turbo Boost can run the i7-820QM at 3.06 GHz for a single core, 2.8 GHz for two, 2.0 GHz for three, and then down to 1.73 GHz for all four cores.
In otherwise-identically configured desktop systems, an Intel® Core™ 2 Duo 3.33 GHz processor took 277 seconds to encode two 30 second segments of HDV 1080p25 footage with a cross-dissolve transition applied across the entire 60 seconds. An Intel® Core™ 2 Quad 2.1 GHz processor encoded the same test in 199 seconds, while the very slowest Intel® Core™ i7-920 (2.8 GHz) encoded it in 70 seconds. The high-end Intel® Core™ i7-965 (3.33 GHz) completed the encoding within 66 seconds. As an interesting side note, even the slowest Intel® Core™ i7 was 100% faster than the fastest previous-generation Intel® Core™2 Quad Extreme QX9770 (3.2 GHz), which clocked 140 seconds. This speaks very favorably for the newly-released Intel® Core™ Mobile i7 (Calpella) processors.
What if you need battery life more than power, though? Vista and Windows 7 both have power saver modes that work with the Intel® Core™ Mobile i7 architecture to underclock the processor cores as low as 1.2 GHz, and the same sensors that control the Intel® Core™ Mobile i7's Intel Turbo Boost technology can also place unused processors into a C6 sleep state, which reduces those cores' power draw almost to zero, significantly extending battery life.
For those who enjoy benchmarks, the 2.0~3.2 GHz Intel® Core™ Mobile i7 920XM placed a CPU score of 30,111 in 3DMark Vantage, a much higher score than the previous mobile king, the 2.53 GHz QX9300 (12,797), and not too much lower than the 2.66 GHz desktop Intel® Core™ i7-920 (39,900).
Intel has taken quite a few evolutionary steps since introducing the Core™ micro-architecture, but the Intel® Core™ Mobile i7 architecture marks Intel's first real revolutionary architecture change in three years, and what a revolution it is!