Verdict: Poor cooling, whichever radiator you choose.

Alphacool submitted two custom kits for this month's water-cooling special but, as the only differences were the sizes of the radiators and number of fans, we decided to review them together.

Both custom kits were supplied with the same CPU waterblock, the theatrically named NexXxoS X2 Bold Highflow. This waterblock, made from a mixture of copper and Plexiglas, is secured to the CPU by the Plexiglas frame, through which you screw four bolts.

These bolts are then secured to both sides of the motherboard by nuts. The entire procedure is explained by six diagrams in a small printed manual, but it lacks the clarity of the documentation supplied with other kits. There is another manual that's supposed to cover the entire kit, but it's a complete travesty, as it's written for a different waterblock and contains no information about the radiator, reservoir or pump.

Such information would have come in handy, as the reservoir and pump are integrated together in what's known as a Laing DDC-Pump 12V Pro AGB. As its name suggests, this is based on the ubiquitous Laing DDC pump - in this case, with 8mm ID instead of the more common 1/2in ID fittings favoured by EK, D-TEK and XSPC. Unfortunately, there's no manual to indicate which barb is the input and which is the output, so make sure that you use the upper barb as the input and the lower barb as the output. The large cap makes filling very easy, but we'd recommend bleeding the system outside the case and as far away from the PC as possible. The reason for this is that as the water exits the input barb, it bounces off the opposite side of the reservoir and bubbles out of the filling hole. At least Alphacool supplies some rubberised screws to prevent vibrations from the pump being transmitted into the case.

On the subject of barbs, both kits use screw-on clamps rather than Jubilee clamps, which is a practical choice, as the tubing is narrow. Alphacool supplied 2m of 8mm ID/11mm OD transparent blue tubing with our custom kits, but we had to be careful as it kinks easily, and there are no anti-kink coils. Like many of the custom kits, Alphacool supplied some ready-mixed coolant: Alphacola. Unlike its namesake, Alphacola definitely isn't for drinking, as it contains anti-freeze and UV dye, making it extremely toxic.The TIM supplied for the CPU waterblock is extremely runny, so it's very difficult to apply in a thin, even layer across the CPU heatspreader. Also included in the box are a large plastic funnel and a handy tool for cutting tubing.

The dual 120mm-fan radiator, the NexXxoS Xtreme II - Rev. 2 continues Alphacool's love of mixing lower and upper-case versions of the letter x in its product names. It was supplied with two 120mm fans, each set to spin at 1,200rpm. The triple 120mm-fan radiator is simply a scaled-up model of the NexXxoS Xtreme II - Rev. 2, and was supplied with three identical 120mm fans. As with most radiators, you can fit another set of fans on the other side to act in a push/pull configuration.

The dual 120mm-fan radiator Alphacool kit struggled to keep our test system cool; the CPU temperature was the same as it was with the Tuniq Tower 120 fitted. Although the water-cooling kit was quieter, this is a pretty appalling result, considering it costs £160 more. At Alphacool's behest, we remounted the CPU waterblock with the input at the bottom (this is usually mounted at the top), but this increased the CPU temperature and after 38 minutes, the CPU overheated so much that Orthos crashed.

Replacing the dual 120mm-fan radiator with the larger triple 120mm-fan model improved matters, but the CPU temperature was still only 3ûC lower than it was with the Tuniq Tower 120 fitted. Again, this is very disappointing given the high cost of this CPU-only kit.

Although these kits only had to deal with the heat from our overclocked and overvolted CPU, they struggled to deliver substantially better temperatures than those of a £33 HSF. Given the terrible documentation, poorly designed reservoir and high price, we can't see any reason to recommend either of them.

• Cases - 21st November 2008
• Motherboards - 24th October 2008
• Gaming Headsets - 26th September 2008
• Dream PCs - 24th September 2008
• Headphones - 12th September 2008
• Media PC components - 22nd August 2008
• PSUs - 14th July 2008

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