Verdict: The best-performing water-cooling kit to date.

Although Swiftech sells a variant of the H2O-220 Apex Ultra with a GPU waterblock, it also produces several high-end components not available in a single retail kit. Unfortunately, these components are not all available from a single retailer, so we've listed the individual components separately on the feature table on p96.

The Apogee GTX CPU waterblock has been in production for some time, but this is first time we've been able to test it. Internally, the Apogee GTX has the same 'diamond-pin matrix' design as the Apogee GT supplied with the H2O-220 Apex Ultra and Vadim custom kits, but it has a different top. It's made from aluminium coated with zinc cobalt, and dominated by 12 heatsink-like fins. The input and output barbs are spaced further apart than they are on the Apogee GT, so water has to travel further inside the Apogee GTX, giving it more time to absorb heat from the CPU. The Apogee GTX is easily secured to the CPU by four screws that pass through the motherboard to a backplate on the other side.

The Northbridge is cooled by another Swiftech waterblock, the MCW30, which is supplied with three different mounting mechanisms, so it's compatible with a wide range of motherboards.

Swiftech supplied us with a prototype of its brand-new Black Pearl waterblock to mount on our graphics card. Rather than designing an entire new waterblock from scratch, the Black Pearl is a combination of several other Swiftech waterblocks, including the MCWRamcool and Stealth VGA. It's smaller than some of the other graphics card waterblocks we've seen this month, but it can cool both the card's GPU and RAM. However, as it doesn't provide water cooling for the graphics card's VRMs, you need to fit a small aluminium heatsink to cool these. The Black Pearl has six holes to mount the barbs, providing maximum flexibility, depending on the shape and size of your case.

Cooling is provided by a MCR320-QP triple 120mm-fan radiator. Like all Swiftech radiators, this has self-purging plenum chambers, so it's easy to fill and bleed. We mounted three Yate Loon D12SH-12 fans on the radiator, but another three fans could be installed on the other side of the radiator. Swiftech supplied three 12V to 7V resistor cables to slow down the noisy fans but, as these aren't available to buy in the UK, we used three RC56 resistor cables from www.quietpc.com

Swiftech doesn't supply 1/2in ID tubing with its high-end kits, instead specifying 7/16in ID tubing. Its slightly wider dimensions provides a higher flow rate than 1/2in ID tubing, but due to its larger size, it's difficult to position inside smaller cases. Thoughtfully, Swiftech supplied some of its own Smartcoil-branded anti-kink coils to help prevent kinks from developing in the tightly angled sections of tubing. Swiftech doesn't supply any pre-mixed coolant, so you should mix Feser Base with distilled/deionised water to prevent corrosion.

Coolant is pumped around the loop by a hefty Swiftech MCP655 pump, yet another rebranded Laing D5. This is one of the most powerful and reliable pumps on the market, but it's much larger than the more compact Laing DDC, so careful planning will be needed to find a suitable space for it inside your case. Like the H2O-220 Apex Ultra, it includes a Swiftech MCRES-Micro reservoir to store the coolant.

As the MCR320-QP radiator was supplied without any instructions, we tested it first with the fans pulling air through it, and then again with the fans blowing air through it. On average, the CPU and GPU temperatures were 2ûC lower with the fans blowing through the radiator, so this is how we'd recommend configuring the fans. With the fans spinning at 12V, the system was very noisy, but it cooled the CPU to 23ûC below the Tuniq Tower 120, and the GPU to 47ûC below the reference Nvidia HSF. With the fans running at 7V, the system proved to be much quieter, yet the CPU temperature was still a very impressive 18ûC below the Tuniq Tower 120 and the GPU temperature 41ûC below the reference Nvidia HSF.

While this custom kit lacks the great documentation that Swiftech supplies with its retail boxed kits, its cooling ability is unbeatable. One of the main selling points of water cooling is to reduce system noise, and even with the fans running quietly at 7V, this selection of Swiftech components is cooler than a polar bear's extremities.

• Media PC components - 22nd August 2008
• PSUs - 14th July 2008
• Multi-GPU graphics - 20th June 2008
• CPU water cooling - 17th June 2008
• Hard disks - 20th March 2008
• Audio hardware - 29th February 2008
• Graphics cards - 24th January 2008

• Antec Mini P180 - Cases
• Turok - Games
• ATI Radeon HD 4870 X2 - Graphics cards
• Cooler Master Cosmos S - Cases
• Lian Li PC-P60 Armorsuit - Cases
• Asus Rampage Formula - Motherboards
• Gigabyte GV-NX96T512H-B - Graphics cards