Zalman TNN 300

The TNN 300 is the smaller sibling of the much larger TNN 500A - a gargantuan piece of metal that will house your PC without the need for active cooling. Like its bigger brother, the TNN 300 works by effectively acting as a giant heatsink: the TNN stands for Totally No Noise. The processor and graphics card are connected to the sides of the aluminium case with copper heatpipes. As these core components heat up, the heatpipes ferry extra heat to the sides of the case. These are ridged to increase surface area and, given sufficient ventilation, the heat evaporates into the room.

While the TNN 500A allows you to create virtually any specification of PC, there are compromises with the TNN 300. Although it's about the same size as a standard ATX case, the heatpipe assembly for the processor takes up so much space that only a microATX motherboard can be fitted. Also, Zalman only guarantees the TNN 300 to work with processors with a TDP (Thermal Design Power) of 70W or less. That precludes using any Athlon 64 processors (which are rated at 89W) and current Pentium 4 processors. A Northwood 2.8GHz Pentium 4 is rated at 70W - any faster and you're on your own. We were also discouraged from using a top-end graphics card as, with only three heatpipes coming from the graphics card cooler, there simply isn't enough cooling. Zalman has provided for those who want to build a system with a bit more power, though: there's a mounting for a 120mm fan at the back, which should provide enough active cooling for faster processors. You'd still have a system without CPU, GPU or PSU fans, which are the main acoustic renegades.

Building a system with the TNN 300 isn't for the faint-hearted. We built ours using an even mix of finesse, improvisation and brute force. We suggest a dry run without thermal paste or screws to give an idea of how it will fit together. It would be all too easy to short a motherboard by accidentally bridging electrical contacts with a heatpipe.

Zalman includes CPU mounts for Socket 478, 775 and Athlon 64 processors, plus nine heatpipes, cooler blocks for the CPU and GPU, and even mini-heatsinks to cool the RAM on the graphics card. Prising the heatsink and fan assembly from your graphics card takes steady nerves, but, once done, you'll appreciate the reduction in noise.

And it's a significant drop. Once built, our 2.8GHz Pentium 4 with its ATi Radeon 9800 was totally silent - not bad for a machine that can still handle the vast majority of games. The only moving, and hence audible, parts were the hard disk and optical drive. The hard-disk mounting comes with a heatsink to further reduce heat build-up, plus rubber grommets to reduce vibration and noise - choose a quiet model, such as the Western Digital Scorpio, and you'll hear it only if you put your head inside the case.

Once running, the side of the PC that was connected to the CPU cooler became uncomfortably warm to touch; in fact, it radiates so much heat that you might not want it sitting next to you. SpeedFan (www.almico.com) reported that our 3.4GHz Prescott Pentium 4 (underclocked to 2.8GHz) had reached a frightening 92C, and after a brief session running on Far Cry the system overheated and shut itself down. However, with the CPU and GPU being cooled in different areas of the chassis, gamers shouldn't need to add too much cooling to make the TNN 300 a near-silent gaming system. We were also impressed when we opened up the system - in spite of the high temperatures on the exterior, the inside of the TNN 300 was cool.