Intel Core i7-2700K
‘Hyper-Threading
does not make a quad processor into an eight-core CPU.’
The logical point for this review of Core
i7-2700K is the Intel Core i5-2500K as the two processors have so many features
in common. They both use the LGA1155 socket, run on P67 and Z68 chipset
motherboards and employ a dual-channel DDR3 memory controller.
There’s another significant similarity, as
these are both K model processors that have an unlocked Turbo Boost setting,
which makes them an absolute doddle to overclock. The K suffix also means that
both the Core i5-2500K and Core i7-2700K have the higher specification Intel HD
Graphics 3000 graphics core that has 12 shaders. Pretty much the best you can
say about the Intel graphics is that they put a picture on the screen and
handle movie playback satisfactorily.
Intel
Core i7-2700K
It is possible to imagine building a PC with
a stonking Core i7 processor and feeble Intel graphics, but it would be
severely unbalanced and would have little or no use for playing games. That
could suit you perfectly if you’re building a workstation but would be unlikely
to fit the bill for home use.
The minor difference between the two
processors we’re comparing is that Core i7-2700K runs at 3.5GBz while Core
i5-2500K is 200MHz slower at 3.3GHz. That leaves two major differences; the
first is that the Core is 5 is a quad-core that processors four threads of data
while the Core i7 employs Hyper-Threading to manage eight simultaneous threads.
The other difference is that the Core i5 costs $255 while the Core i7 sells for
$405. This means that the combination of Hyper-Threading and 200MHz of extra clock
speed costs exactly $150, which seems like a steep price to pay.
It’s worth pointing out that
Hyper-Threading does not make a quad processor into an eight-core CPU. If the
four cores are fully loaded and are running efficient software that can use the
cores to the max, then Hyper-Threading has no part to play. The technology
shows a benefit when the software doesn’t work so well and one thread gets
delayed, at which point Hyper-Threading switches its efforts to another thread
and then jumps back when the problem has been solved.
You can see the benefit of Hyper-Threading
in the 3DMark 11 Physics test where Core i5 scores 6,686 marks and Core i7
romps home with 8,854 marks. That’s an improvement of 32%, where no more than
6% can be attributed to the extra clock speed, which leaves 26% credit at the
door of Hyper-Threading.
The irony here is that AMD Bulldozer is a
genuine eight-core processor that suffers from poor performance and high power
consumption, apparently because the cores are arranged in pairs. By contrast,
Intel uses four cores that are arranged in virtual pairs and the system works
very satisfactorily.
There is a downside because Core i7-2700K
draws 20W more power than its slower Core i5 brother under load, which rises to
a 30W differential when the CPU is overclocked to 4.6GHz.
In an ideal world, we would recommend Core
i7-2700K without hesitation but the steep price gives us pause for thought.
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Details
Price: $405
Manufacturer: Intel
Website: www.intel.com
Required spec: Socket LGA1155,
dual-channel DDR3
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Intel
Core i5-2500K - Low power draw, quad-core, high performance and simple Turbo
overclocking add up to a superb piece of silicon.
Intel
Core i7-2700K – the addition of Hyper-Threading gives the Core i7 extra zip,
but the high price leaves a bad taste in the mouth.
