More about I7

Faster memory access
The reason for this platform shift has to do in part with a fundamental design change in Intel’s CPU architecture. As has long been rumoured, Intel has finally adopted an integrated memory controller into its Core i7 CPUs. What this means is that instead of the CPU communicating with a separate controller on the motherboard before it can talk to the system memory, Core i7 can save a step, and essentially receive data from the system RAM directly.

Intel’s new Extreme Motherboard DX58SO.

AMD adopted this integrated controller strategy in the early days of its Athlon dual-core processors, and it was one of the factors that led the company to dominate Intel’s competing Pentium D CPUs of that generation. Through superior design since then, Intel has regained its performance lead over AMD, and we suspect that by adding the on-chip memory controller to Core i7, Intel has only made it more difficult for AMD to find a design advantage moving forward.

A potential complication here is that the new memory controller has three channels to the RAM. That means that — unlike most desktop set-ups, which involve two or four memory sticks — Core i7 systems will want memory sticks in multiples of three. This is why Intel shipped our test system with only 3GB of RAM (we got creative with a 2×1GB, 1×2GB RAM configuration for 4GB total for testing), and why in high-end PCs that use the new X58 platform, 3GB, 6GB and 12GB configurations will be common. X58 will also only support DDR3 RAM, whose prices have thankfully come down over the past year.

Four cores, sometimes eight
If you’ve followed Intel’s chip designs over the years, the term ‘Hyperthreading’ shouldn’t be unfamiliar. This technology lets Intel simulate more processing threads on top of its old dual-core Pentium 4 chips. It abandoned that strategy with the Core 2 family, but Intel has resurrected it with Core i7, and it’s why you’ll see eight processing threads when you bring up Windows’ system performance screen. Few day-to-day programs will benefit from Hyperthreading, and it’s more of a situational benefit for processing reliability and the scant few applications that can actually support so many threads. Core i7 will eventually hit eight native cores on a single CPU, or 16 processing streams with Hyperthreading, but Intel has not made it clear when that will happen. It may be worth the wait if you know you’ll need that much parallelism, but few ordinary users will.

Multi-graphics agnostic
Another significant change with the Core i7/X58 landscape had to do with graphics cards. Intel’s Skulltrail platform of last year supported both standards as well, but the specialised CPUs that made the board worthwhile were prohibitively expensive. With the X58 chipset, yes, it comes on an expensive motherboard, but you can purchase a Core i7 chip to go with it for less than $300 (~£191). The Core 2 Extreme QX9775 Skulltrail CPU started at $1,500 (~£957). Gamers who stay current with graphics cards should be especially happy with this flexibility, as changing 3D card vendors will no longer require a wholesale system rebuild.

We tested both SLI and Crossfire set-ups on our Core i7 testbed and found both worked without trouble, requiring nothing more than installing the hardware and appropriate graphics driver software as you would normally. As for their performance, AMD has issued a series of so-called ‘hot-fix’ drivers to improve compatibility and frame rates of its cards with various PC games, which suggests that its software still needs to work out a few kinks on X58. Nvidia has not been shy to point out this fact (its beta drivers have worked fine).

A quicker path
Finally, the last major change with Core i7 is the introduction of what Intel is calling the QuickPath Interconnect (QPI). Essentially this is the Intel version of AMD’s HyperTransport interface between the CPU and the chipset. The major impact of the QPI for users is that Intel employs different QPI ratings to distinguish the Core i7-965 Extreme Edition from the non-Extreme Core i7 chips. Rated by Gigatransfers per second (Gigatransfers, or GT, refers to a million transfers of data), the Extreme Edition comes in at 6.4GT/sec, where the non-Extreme versions handle only 4.8GT/sec. In addition to that speed advantage, Intel also ships the Extreme version with an unlocked clock multiplier, which means it can be overclocked. The standard Core i7’s will have to remain at their shipping speeds.

To put the Core i7-965 Extreme Edition in perspective, we compared it with the year-old Core 2 Extreme QX9650. The Core i7 has a faster clock speed and an L3 cache shared by the four cores that’s four times larger than that of the older chip. With the integrated RAM controller on Core i7 replacing the need for a frontside bus, the platforms are quite different from each other, so the specs don’t tell the whole story. The performance results speak more clearly.

The Core i7 chip is faster than the QX9650 on every test, but we were most impressed by the Cinebench multicore test and the Far Cry 2 benchmark, where Intel’s new CPU established a sizable performance advantage. Gamers and digital media editors may have assumed that Core i7 is worth their attention: as we can see from our testing, any such assumption is clearly justified.

We expect the web will flood with reviews of the entire Core i7 family at the same time that this review launches. We encourage anyone considering a new CPU purchase to read as much coverage as possible to make the most informed buying decision. Any CPU with a $999 (~£637) price tag merits careful consideration.

Power consumption
You’ll note from our power consumption tests that the Core i7 and the QX9650 consume almost the exact same amount of energy both at idle and while under load. We didn’t expect major gains here, as both chips use the same 45nm process, run at a similar clock speeds and with similar numbers of transistors. Intel typically gains more power efficiency with chips introduced in a ‘tock’ year, which involves more efficient manufacturing of an existing architecture, than from a ‘tick’ year such as this. The Core i7-965 Extreme may have improved its relative power usage, in that it uses fewer transistors to do more work and at faster clock speeds than the older Core 2 Extreme chips. But anyone building a system with this new processor should expect to need an equivalently beefy power supply — especially if you intend to add multiple graphics cards and hard drives.