Opening the taps
We were able to overclock the front-side bus of Gigabyte's X48T-DQ6 motherboard to a whopping 500MHz with default chipset voltages when we reviewed the board last month, so it seemed like a perfect platform on which to push the X3320. The X3320's default 7.5X multiplier is only unlocked for lower values (and then only down to 6X), so we pushed the chip by increasing the speed of the front-side bus, testing for stability with Prime95 crunching on all cores along the way. We also adjusted the memory bus divider to ensure that our DIMMs operated at or below their rated speed, removing them as a potential hindrance.

Overclocking the X3320 was a breeze up to a front-side bus speed of 435MHz. The chip didn't even need any extra voltage, although as soon as we deviated from its stock 2.5GHz clock speed, CPU-Z reported that the core voltage had increased from 1.120V to 1.136V.

Our 435MHz front-side bus yielded a processor clock speed of 3.26GHz, which is a healthy 30% boost over the CPU's default frequency. Heck, 3.26GHz is even faster than Intel's flagship Core 2 Extreme QX9770, which runs at 3.2GHz and sells for an absolutely obnoxious $1500.

Unfortunately, our X3320 just wasn't stable beyond 3.26GHz. At 3.3GHz, Prime95 started spitting out errors with at least one of the four instances we ran to stress test the CPU. Since we were still using the chip's default voltage, we cranked up the juice to see if that might help. But it didn't. Even at as much as 1.4V, our X3320 just wasn't 100% stable at 3.3GHz. We tried higher speeds, too, and although we could post and even get into Windows at up to 3.5GHz, the system crashed under load. Getting a quad-core CPU to boot into Windows is one thing, but having all four of its cores behave while under load is considerably more difficult, it would seem.

Just to be sure, we swapped the X3320 into an nForce 790i SLI motherboard to see if it would run any faster on an Nvidia platform. No such luck. The chip stalled out at 3.26GHz, just like on the Gigabyte X48 board.

To provide a glimpse of what kind of performance increase you can expect from a Xeon X3320 overclocked from 2.5 to 3.26GHz, I ran a few benchmarks at stock and overclocked speeds. When overclocked, the system ran with a 1305MHz memory bus, which is a little slower than the effective 1333MHz memory clock of our stock config.

That's a healthy performance increase from what's essentially a "free" overclock at default voltage. Not bad at all.

But what about operating temperatures? Surely there's a penalty involved with pushing the X3320's clock speed 30% higher than what Intel prescribes for the chip. We busted out Everest to monitor CPU temperatures at idle and under load and were a little surprised by the results.

At idle, there's no difference in operating temperature between the chips. However, under load, the overclocked config runs about six degrees warmer—not much, all things considered.

Everest also reports individual core temperatures, and while these values were much higher than the reported "CPU temperature," there wasn't much difference between the stock and overclocked setups. Our stock-clocked Xeon reported core temperatures between 47° and 50°C at idle and between 63° and 67°C under load. When pushed to 3.26GHz, core temperatures rose to between 48° and 51°C at idle and between 67° and 71°C when subjected to our four-way Prime95 load.

Next, we used a Watts Up? Pro power meter to test total system power consumption, sans monitor and speakers, at the wall outlet.

There's only a marginal difference in idle power consumption between our Xeon X3320 at 2.5 and 3.26GHz. Under a Prime95 load, however, the overclocked system pulls nearly 17W more power than our stock config. We're more than willing to swallow a 9% increase in peak power consumption for a 30% boost in clock speed, though.