Intel's Core 2 Quad Q9300 processor

By Koushik Saha on 20.4.08

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We first reviewed a 45nm Intel processor back in September, and since then, the CPU maker has been ramping up production and slowly transitioning to 45nm chips across its product lines. Two of the final steps along Intel's path to 45nm ubiquity are of great interest to PC enthusiasts: budget dual- and quad-core processors. We like budget processors for obvious reasons—they're cheap, like us—and not-so-obvious ones—they tend to have the most overclocking headroom. We especially like the idea of budget 45nm Core 2 processors for yet another reason: they promise to combine a potent punch with modest power draw.

We have two of these chips on the bench today, and they're just now becoming widely available. The Core 2 Quad Q9300 is Intel's most affordable quad-core processor, and it promises to supplant a long-time favorite of ours, the Core 2 Quad Q6600, by offering additional goodness at the exact same price. The Core 2 Duo E7200, meanwhile, is Intel's cheapest 45nm dual-core CPU and a potential goldmine of overclocking potential. As is our dubious custom, we've tested these two processors against a whole slew of would-be competitors and wholly inappropriate alternative options.The Q9300 is built from the same basic ingredient as Intel's other 45nm processors: the dual-core chip code-named Penryn. To create a quad-core processor, Intel groups two Penryn chips together into one package. The two chips operate more or less independently, communicating only by means of the front-side bus. In that sense, the Q9300 is really not much different from the Core 2 Extreme QX9650 introduced last October.

What makes the Q9300 distinctive is its level-two cache. Each Penryn chip has 6MB of L2 cache onboard, dynamically partitioned and shared between the chip's two cores. That gives most Penryn-based quad cores a total of 12MB of L2 cache. (Math is hard.) In the Q9300, however, each chip has half of its L2 cache disabled, so the processor has a two-by-3MB cache config, for a total of 6MB of L2.

Yep, it's neutered. But Intel's willing to sell it cheaper that way. The Q9300 runs at a default 2.5GHz on a 1333MHz bus and lists at $266. Factor in Penryn's higher per-clock performance, and the Q9300 beats out its predecessor on multiple fronts. The Core 2 Quad Q6600 offered a 2.4GHz core clock, 1066MHz bus, and an older version of the Core microarchitecture for the same price.

How much will the Q9300's smaller cache size affect its performance? Well, like so many things, it depends. If a program's working data set is too large to fit into a 3MB cache but will fit comfortably into a 4MB or 6MB cache, then the difference may be pronounced. If not, then the difference may be zip, nada, nothing. The thing is, these days, caches are becoming large enough that we're getting well into the realm of diminishing returns for larger caches, especially in common desktop applications. You'll see what I mean when you see the Q9300's performance results.

Oh, and the Q9300's TDP (thermal design power) rating is 95W, down from 105W in the Q6600, thanks to the magic of Intel's high-k 45nm fab process.

The Q9300's closest competition from AMD is the Phenom X4 9850 Black Edition. Intriguingly, that processor is also clocked at 2.5GHz and features a single-chip, native quad-core design with 2MB of L3 cache shared between all four cores. The Phenom 9850 Black Edition lists for about 30 bucks less than the Q9300, though, and has an unlocked multiplier to make overclocking easier. We'll have to see whether the Q9300 can back up its price premium.

If the competition from AMD isn't trouble enough, the Q9300 also has to contend with a stable mate, the Core 2 Duo E8500, which also lists at $266. This is a full-on Penryn dual-core with 6MB of L2 cache and a clock speed of 3.16GHz. The Q9300 will have to make its case against the E8500 on the strength of its two additional cores.

Oh, and since we're on the subject of 45nm Core 2 Quads, I've also thrown in some results on the following pages for the Core 2 Quad Q9450. This puppy has a full 6MB of L2 cache per chip and runs at 2.66GHz on a 1333MHz bus. Like the Q9300, its TDP is 95W. At $316, it too may be a fairly compelling value.

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