Intel Core i7 920 review

It's not often we see an entirely new processor architecture. However, Intel's new Core i7 range, which until recently was referred to by its Nehalem codename, has some intriguing differences to the current Core 2 line-up.

Most remarkably, Intel has dispensed with a traditional frontside bus (FSB). Instead, there's the new QuickPath interface, a memory controller that's built into the processor itself. This works much like AMD's HyperTransport memory controller, and should give faster memory access times. QuickPath supports only DDR3 memory, though, and is triple-channel rather than dual-channel. This means you'll need to buy kits consisting of three DDR3 modules and discard your old pairs of DDR2 memory.

Because of these changes, Core i7 processors require a motherboard with the new Intel X58 chipset. All the proposed X58 motherboard designs have six memory slots, which is enough for two kits of three modules. We were forced to use an Intel prototype board for our testing, but motherboards from popular manufacturers such as Foxconn, Asus and Gigabyte should be available by the time you read this.

Just like the Intel Core 2 Quad range, all Core i7 processors have four physical cores, which means you can run multiple applications with ease. However, the Core i7 range also uses Hyper-Threading. This was present in Pentium 4 processors and, more recently, in Intel's Atom. It allows each core to process two threads of information simultaneously. Based on our previous experience with Hyper-Threading, this will help boost performance, but it won't double it.

We tested the Core i7 920, which has a clock speed of 2.66GHz. This makes it the slowest of the three initial Core i7 releases; the 940 runs at 2.93GHz, and the 965 Extreme Edition at 3.2GHz. All models have 256KB of L2 cache for each core and an 8MB L3 shared cache - a flexible arrangement that shouldn't result in memory bottlenecks.

We weren't that impressed with the Core i7 920's performance in PCMark Vantage, with its overall score of 5,694. Compare this with a PC that has an Intel Core 2 Quad Q9550, which scored 5,942 overall. The Q9550 may have a slightly higher 2.83GHz clock speed but its similar price (around £25 less than the 920) makes it a fair comparison.

Core i7 processors use the same 45nm fabrication process as the latest Core 2 processors. Despite this, they have a higher thermal design power (TDP) of 130W, compared to the 95W TDP of most Core 2 Quad designs. This means you'll need a bigger heatsink to keep a Core i7 processor cool, which is likely to mean a bigger or louder PC.

Our initial impressions of the Core i7 920 aren't great. When you add the cost of a motherboard and 3GB of DDR3, you're looking at a staggering £550 including VAT. We're hoping that retail systems, with finalised motherboard designs and updated drivers, will perform better than our prototype. We'll cover two such systems in next month's Shopper. Until then, we'd advise against rushing out to buy Core i7.

Author: Mike Jennings