Intel Core i7
Intel Core i7 is a family of three Intel Desktop x86-64 processors. Core i7 is the first Intel family to be released using the Intel Nehalem microarchitecture and is the successor to the Intel Core 2 family. All three models are quad-core processors.The Core i7 identifier applies to the initial family of processors codenamed Bloomfield. The moniker Core i7 does not have a deeper meaning, but continues the use of the successful Core brand.
Intel announced that the family is due to be launched on November 17,
2008. Core i7 chips and motherboards were being sold prior to the launch date by some retailers. The processors were also available for pre-order from major online retailers.The Intel sales embargo was lifted at one minute after midnight on 16 November in Tokyo, and Stores stayed open to start selling at that time.
Intel released official pricing information on November 3, 2008. and the first benchmarks also appeared online.
Features
Nehalem represents the largest architectural change in the Intel x86 family since the Pentium Pro in 1995. The Nehalem architecture has many new features. The ones that represent significant changes from the Core 2 include:
- FSB is replaced by QuickPath interface. Motherboards must use a chipset that supports QuickPath. As of November 2008[update], only the Intel X58 does this.
- On-processor memory controller: the memory is directly connected to the processor.
- Three channel memory: each channel can support one or two DDR3 DIMMs. Motherboards for Core i7 have four (3+1) or six DIMM slots instead of two or four, and DIMMs should be installed in sets of three, not two.
- Support for DDR3 only.
- "Turbo Boost" technology allows the cores to intelligently clock themselves to 133MHz or 266MHz over the design clock speed so long as the CPU's therma l requirements are still met. This mode isn't enabled when the CPU is manually over-clocked by the user.
- Single-die device: all four cores, the memory controller, and all cache are on a single die.
- Re-implemented Hyper-threading. Each of the four cores can process two threads simultaneously, so the processor appears to the OS as eight CPUs. This feature was present in the older Netburst architecture but was dropped in Core.
- On-die, shared, inclusive 8MB L3 cache.
- Only one QuickPath interface: not intended for multi-processor m otherboards.
- 45nm process technology.
- 731M transistors.
- Sophisticated power management can place an unused core in a zero-power mode.
Drawbacks
- The Core i7 or at least, any current motherboard for the Core i7 as of November 13, 2008 (two ASUS boards, two MSI boards, a DFi board, an ECS, an EVGA and the Intel DX58SO, gigabyte board -- data available from manufacturer website) does not support ECC memory.[citation needed] Some experts, such as Daniel Bernstein, recommend that systems lacking ECC support should be avoided unless occasional errors are acceptable.
- As of 2008-11, DDR3 SDRAM costs significantly more per gigabyte than equivalent-speed DDR2.
Processors
- The clock speeds listed here are for normal mode. Speed on a single core can increase by up to 400MHz when the other cores are turned off.
- The 965 XE has separate unlocked multipliers for memory and cores.
- Memory speeds up to DDR3-2000 are possible, but not supported by Intel
- Core clocks of up to 4GHz have been reported, but are not supported by Intel
- The processor has a Thermal Design Power of 130W and will slow itself down if this power is exceeded. This feature can be disabled.
- Prices are per unit in lots of 1000 in USD
Performance
A 2.93 GHz Core i7 940 system has been used to run a 3DMark Vantage benchmark and gave a CPU score of 17,966. The 2.66 GHz Core i7 920 scores 16,294. An earlier generation Core processor, 2.66 GHz Core 2 Quad Q9450, scores 11,131.
AnandTech tested the Intel QuickPath Interconnect (4.8 GT/s version) and found the copy bandwidth using triple-channel 1066 MHz DDR3 was 12.0 GB/s. A 3.0 GHz Core 2 Quad system using dual-channel 1066 MHz DDR3 achieved 6.9 GB/s.
Overclocking will be possible with the 900 series and a motherboard equipped with the X58 chipset. In early October 2008, reports surfaced that it will not be possible to use "performance" DDR3 DIMMs that require voltages higher than 1.65v, because the integrated memory controller within the Core i7 will be damaged. Some tests, however, have demonstrated that the voltage limit does not apply, like on an MSI board, and manufacturers can choose to bond CPU voltage to memory or not. By the end of that month, performance memory vendors had announced 1.65v DDR3 memory kits with speeds up to 2GHz.
Some early articles suggested that i7's design is not ideal for gaming performance. In a test done on leaked hardware, a Core i7 940 compared to a QX9770 shows the Core i7 is slower than Yorkfield clock for clock in 2 games while being faster in the other two. The difference in all cases is small.However, more recent testing done on all speeds of official hardware with final drivers and BIOS revisions show that Core i7 at the very least beats Yorkfield clock-for-clock, and in most cases exceeds it by an average of about 17%.
In the single-threaded Super PI 1M test, a Core i7 920 running at 2.66 Ghz finished the test in 15.36 seconds, while a QX9770 (3.2 Ghz) did the test in 14.42 seconds, so the Core i7 executed 20% more instructions per clock cycle on this test.
The Core i7 has three memory channels, and the channel speed can be selected by setting the memory multiplier. However, in early benchmarks, when the speed is set higher than a threshold (1333 for the 965XE) the processor will only access two memory channels simultaneously. A 965XE has higher memory throughput with 3xDDR3-1333 than with 3xDDR3-1600, and 2xDDR3-1600 has almost identical throughput to 3xDDR3-1600.
Since the Core i7 is a quad-core processor, Hyperthreading cannot yield any performance improvement for application workloads with fewer than five simultaneous threads when all the cores are fully powered on, and some applications will suffer a performance degradation when hyperthreading is enabled.Hyperthreading will provide its best improvement when the workload has eight or more simultaneous threads.
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