Verdict: A water-cooling system to fit in your case's free drive bays.

While some kits in this Labs test were supplied with bay reservoirs, everything comprising Thermaltake's Big Water 760i, bar the waterblock, is designed to fit in a single full-height 5.25in drive bay (or two 5.25in drive bays if you don't have a prehistoric full-tower case).

This rather curious arrangement means that the Big Water 760i's radiator is mounted horizontally, so that hot air is blown into the drive bay above. This, of course, could be catastrophic if the bay above contains a drive - realistically, you'll need several free drive bays to make the best use of the Big Water 760i. Even then, we aren't convinced that the arrangement works very well, as most cases aren't designed to provide much ventilation for their 5.25in drive bays.

A bigger issue is that this arrangement negates one of the big advantages of water cooling over air cooling - that of expelling heat from the case.

The tiny waterblock looks more like a copper shellfish than a serious piece of cooling hardware, but at least it's easy to mount on an LGA775 system. Although the tubes are attached to the waterblock by screw-in fittings, they're extremely stiff and you'll need a spanner to tighten them. Theoretically, you should be able to fill the Big Water 760i outside the case, as the tubes are fitted with quick-release connectors that are supposed to self-seal to prevent leaks. However, the seals aren't particularly effective, and the pump is so weak that you'll need to top up the radiator with the supplied green coolant to dispose of excess air when you attach the tubes.

The weedy pump meant that it took a long time to bleed the Big Water 760i. Once up and running, our stress test ran for just five minutes before the CPU overheated so much that the thermtrip switched off the entire PC. Unless you like your CPU to toast itself every few minutes and want bubble-filled pipes, the Big Water 760i is best left to rust in peace.

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• Multi-GPU graphics - 20th June 2008
• CPU water cooling - 17th June 2008

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