Verdict: Bigger isn't always better

The Exos-2 is the successor to the Exos, which has technically now been discontinued, although it's still very easy to get hold of.

The most apparent changes are the replacement of the triple 80mm-fan radiator with a dual 120mm fan radiator, and the widening of the tubing from 6mm ID to 10mm ID. The Exos-2 also has more fan speed settings, ten as opposed to three, and three temperature probes.

Other than the increase in tubing size, the new CPU-300-V10 waterblock is almost the same as the CPU-300-H06 used with the Exos. Unfortunately, you still have to go out and buy the Athlon 64 (CPU-A03) and LGA775 (BKT-CP505K-E) mounting kits separately.

One feature that has been removed from the Exos-2 are the self-sealing connectors, which have been replaced with standard screw-on connectors. However, the biggest issue we had with the Exos-2 was when trying to bleed it of excess air. No matter which method we tried, we couldn't remove all the air from the system. At one point, we almost succeeded, but within a few minutes air was circulating back around the system, and all the excess water was being pumped out of the filling hole like some sort of geyser at a nature reserve.

At speed setting 1, the fans are, to all intents and purposes, silent, while at ten they're very noisy. While running at setting 1, the Exos-2 couldn't cool our Pentium 4e sufficiently to stop the automatic thermal protection kicking in and shutting down the PC. However, at setting 10 the CPU was 21ûC cooler than it was with the reference Intel HSF. On our Athlon 64 test rig, it cooled the CPU to between 10ûC and 21ûC below the reference AMD HSF. In the real world, you'd want to find a balance between noise and cooling for your particular CPU.

At around £270, the Exos-2 is £80 more expensive than the Exos and offers very little extra for your money. If you want an external water-cooling kit then we'd suggest buying an Exos before it disappears for good.

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