Intel Core i7 processor review

Today is Intel Core i7 day. You'll find lots of coverage of the new processor and the X58 chipset that supports it right here. We have everything from technical analysis so hard core it will make your brain boil to benchmarks of a literally record breaking machine based on the fastest Core i7 chip of all.

It's a ridiculously impressive new processor, so it's well worth getting to grips with all the new technology. But if what you really want is a quick guide to the chip itself - what makes it tick and how quick it is - read on.

The big news with Core i7 is improved multi-threaded grunt. To pull that off, Intel has created a much more elegantly architected CPU with added on-die features. Most of what used to be found in the northbridge chip on the motherboard has now been integrated into the Core i7's own silicon die.

That includes the memory controller and much of the system I/O. The latter takes the form of the new uber-wide Quick Path Interconnect (QPI) that can shunt over 25GB in and out of the Core i7 every second. The idea is to provide more bandwidth to feed all those data hungry execution cores.

Unprecedented levels of raw bandwidth

And boy, do those cores get fed. Thanks to the addition of an extra memory channel - for a grand total of three - Core i7 packs an unprecedented 18GB of raw bandwidth. That's literally three times as much as previous Intel processors.

Of course, AMD's CPUs already have on-die memory controllers, but with only two channels and no support for DDR3 they typically only enjoy about half the bandwidth of Core i7. Incidentally, like AMD's quad-core Phenom chip, the Core i7 is a truly monolithic, single-die processor. No longer will Intel bodge up quad-core processors by cramming a pair of dual-core chips into a a single processor package.

Along with the added on-die features, Intel has revved its latest processor with further features designed to give a boost to both old fashioned single-threaded applications and the latest highly-parallelised programs such as media encoding.

HyperThreading returns

The biggest headline grabber is the re-emergence of HyperThreading. It's a feature last seen on the Pentium 4 Netburst CPU family and allows each core to crunch two software threads simultaneously for improved multi-threading and multi-tasking performance.

Since all Core i7 are quad-core chips, that means you'll see no less than eight logical processors when you fire up Windows Task Manager. That's a pretty sexy sight.

Next up is Turbo Mode. The short version of the Turbo Mode story is the ability to overclock individual cores according to work load. The aim is to make the most of the thermal limits of the chip when only one or two cores are under heavy load. Whatever the advertised clock frequency of a gvien Core i7 is, add 266MHz to that and you have the top speed a single core can run at.

Raw performance

Intel has also tweaked the cores themselves in a number of areas, including the addition of a few new SSE instructions for extra multi-media goodness and a new three-level cache memory hierarchy.

And for the record, all those architectural changes also bring a new processor socket, known as LGA 1,366. A new motherboard is therefore a bare minimum requirement to get in on the action.

As for the specifications of the Core i7s available at launch, there are three models. The entry level chip is the 2.66GHz Core i7-920, yours for £200, or perhaps a touch less. Next up is the 2.93GHz 940 processor, likely to sell for £400.

Topping things out is the inevitably expensive 965 Extreme Edition. It costs a cool £1,000, runs at 3.2GHz and adds a few overclocking-friendly features such as an unlocked multiplier. All three chips have 8MB of L3 cache and support up to 24GB of 1,066MHz DDR3 memory.

Exceeded expectations

But what about performance? In truth, our expectations weren't all that high. Mainly, that's because Intel's existing Core 2 processors are so damn good, it was hard to imagine anything significantly bettering them much less blowing them away.

Of course, the Core i7 cares not a jot about our preconceptions. In our multi-threaded benchmarks, it duly proceeds to beat the Core i7 to a bloody, whimpering pulp. It's around 60 per cent quicker in the X264 video encode test than the best Core 2 processor, for example. That's almost silly.

While its superiority isn't always that spectacular, a performance advantage of around 40 to 50 per cent is typical in most multi-threaded applications including image rendering and media encoding of various types.

As for how AMD's Phenom compares, it's an absolute massacre. Intel's finest is now often twice as quick as the best AMD can deliver.

That said, the Core i7's single-threaded performance is a bit less impressive. It seems the individual cores aren't a major advance on the Core 2 architecture. Likewise, it's a little disappointing to note that power consumption has gone up a fraction.

We had been lead to believe that greater feature integration would have the opposite effect. Finally, HyperThreading appears to occasionally have negative effect on performance when only a handful of CPU-intensive threads are being processed.

But those reservations are pretty small beer compared to the performance smörgåsbord the Core i7 cranks out most of the time.