Zotac Nitro OC Controller

Verdict: Very orange hardware-based overclocking tool.

The Nitro OC Controller from graphics card manufacturer Zotac is a gizmo that allows you to overclock your Zotac graphics card at the push of a button. The Nitro is guaranteed to work with any Zotac card that has a GeForce 8-series GPU or higher, although it also works with a wide range of non-Zotac GeForce graphics cards. Compiling a list of compatible cards is tricky, though, as compatibility depends on the manufacturer of the graphics card not significantly altering the card's BIOS from the Nvidia spec. Zotac also points out that using the Nitro with a Zotac card won't invalidate the graphics card's warranty, which certainly isn't the case with cards from other manufacturers.

The Nitro allows you to increase the GPU core, stream processor and memory frequencies independently in 5MHz increments. This isn't just useful for those who are wary of overclocking, as it also opens up other possibilities.

Testing an overclock usually means placing your overclocked card under 100 per cent load, but Zotac points out that games rarely put a GPU or graphics card memory under full load. In this scenario, the Nitro might be more useful than overclocking software, because you can apply the overclock while the game is running, and therefore gauge the performance and reliability as you go. You could potentially also use the Nitro to achieve the best possible 3DMark scores by adjusting your overclock between each of the tests.

The Nitro can also supposedly control the speed of the fan on your graphics card, although this feature didn't work with our sample. Zotac tells us this is due to an issue with the ForceWare 180.47 driver, which Nvidia is in the process of fixing. Similarly, the ability to save overclock profiles on the Nitro didn't work either, although Zotac told us it had resolved the problem just as we were going to press.

The three buttons on the front of the device are all you need to overclock your graphics card via its clear VFD, and the Nitro is straightforward and easy to use. The overall build quality is relatively solid, even if the lurid orange colour does resemble that of a stringy, artificial cheese-based snack.

With a wealth of overclocking applications available on the Internet - most of which are free - the Nitro was going to have a hard time justifying its considerable £75 price. We decided to pit the Nitro against RivaTuner (http://www.guru3d.com), which is free and provides so many GPU tweaking options that most of them are a mystery to many people. However, two clicks give you control over your GPU core, stream processor and memory clocks.

We ran Crysis: Warhead at 1,680 x 1,050 with 2x AA so that any frame rate increases would be noticeable, and used a Zotac GeForce 9800 GTX+ AMP! card in our testing. At stock speeds, this card ran Warhead at a minimum of 10fps and an average of 16fps. Using RivaTuner, we managed to increase its GPU frequency from 756MHz to 841MHz, the stream processors' speed from 1.89GHz to 2.025GHz and the memory from 1.15GHz (2.3GHz effective) to 1.275GHz (2.55GHz effective). Finding the maximum stable overclock for the game required a lot of Alt-Tabbing, but the process took only around 25 minutes of serious concentration and experimentation. Despite the hefty increase in frequencies, disappointingly we saw no extra gaming performance, with the minimum frame rate staying at just 10fps.

The process was much easier on the Nitro, and we quickly ramped up the speeds to the stable maximum. The Nitro hit exactly the same maximum frequencies as we had managed with RivaTuner, however, so again, the overclock added no extra performance.

We were worried that our overclocks weren't being applied, despite confirmation from GPU-Z, so we fired up 3DMark06, which is very sensitive to graphics card overclocks. At stock speed, our test rig scored 15,448, but with our tried and tested overclock applied using RivaTuner, the system hit 16,192, an increase of 744 points.

RivaTuner can't increase GPU clock speeds during a 3DMark run, which gives the Nitro an edge in this test. As 3DMark testing is all about the score, we pushed our card to the brink for each test without worrying about artefacts. However, despite spending hours finding the maximum frequencies of the graphics card for each test and enduring headache-inducing artefact-speckled visuals, we only added a further 104 points to our 3DMark06 score, hitting 16,296.

Conclusion

The great thing about overclocking is that you should be able to obtain a performance boost for no extra cost, but the Nitro breaks this fundamental law. In games, it couldn't provide any more performance than a free application, even though it did save a little time. Competitive benchmarkers, who might want to apply different graphics card overclocks for each test of a benchmark suite, may find the Nitro useful. However, everyone else should either spend the Nitro's £75 price on a better graphics card, or stick to using software tools.