FSP Booster X3

Verdict: Boost your PC's power without replacing your PSU.

Until recently, if you were thinking about buying a new power-hungry graphics card, but didn't think your current PSU could handle the extra load to support any new purchase, you'd have to pull apart your PC and install a new PSU as well. Those days are now behind us, thanks to the introduction of the world's first graphics card PSUs by FSP and Thermaltake.

As these PSUs only provide a 12V output for graphics cards, the idea is for them to complement your existing PSU. Both the FSP and Thermaltake are designed to slot into a spare 5.25in drive bay. Unfortunately, this means that they both create a lot of extra wiring; in addition to the two PCI-E power cables that each provides, there's a pass-through cable that needs to be screwed into an expansion slot on the back of the case to allow connection to the mains for power. Also, each graphics card PSU has to be connected to the PC, so that it will switch on at the same time as the rest of the system.

The FSP is activated by power provided by a Molex connector - which is a fairly elegant arrangement - while the Thermaltake has a 24-pin ATX pass-through cable with a breakaway 3-pin connector. These three pins echo the signals that the motherboard sends to the ATX PSU, so that the Thermaltake powers up at exactly the same time as the rest of the PC. The downside to this method is the bulky 24-pin ATX pass-through cable, which will add a lot of cable clutter to your PC.

The FSP claims to have two 12V rails, each capable of outputting 12.5A for a maximum combined load of 25A, or 300W. The Thermaltake is slightly less powerful, with two 12V rails, each rated at 10.5A for a maximum combined load of 21A, or 252W. Both models have CrossFire and SLI certification, although a closer look at www.ati.com and www.slizone.com reveals a couple of caveats. While both PSUs are certified by ATi to support X1950 CrossFire, your PC will still need at least a 450W PSU. This is because graphics cards aren't solely powered by their PCI-E connectors, but also by the 16x PCI-E slot on the motherboard, which is powered by the ATX PSU. For people with Nvidia cards, both PSUs are certified to support up to GeForce 7950 GX2 SLI, but GeForce 8800 GTS and GTX SLI isn't supported.

The FSP is housed inside a heavyweight steel chassis and cooled by two 40mm fans that draw in air at the front through a slotted plastic panel, and expel it through slots in the rear panel. The fans are temperature-controlled, and are very quiet at up to 50 per cent load; at full load, however, they emit a deeply distressing high-frequency whine that could be heard through the wall in the room next to the test lab. Protruding from the front panel is a sheet of blue LED illuminated curved transparent plastic that looks like the lens piece from a ski mask.

The Thermaltake is made from much more lightweight steel and plastic, but it's much quieter than the FSP, as its single temperature-controlled 40mm fan is tucked away at the back, so any noise is partly muffled by the PC case. As the front panel is dominated by a large wire mesh grille, the fan doesn't have to spin particularly fast, and the only noise you can hear is a low-frequency whooshing sound.

We tested both PSUs according to the ATX spec, which cites that the output of 12V rails has to be within plus or minus 10 per cent of 12V. We carried out the testing at Enermax's lab, which is the same place that we used to test the PSUs last issue. By using the same Chroma 6314 load testers we use to test ATX PSUs, we were able to load up each rail to its maximum rating and check if the output was within the limits of the ATX spec. Both PSUs were able to deliver a stable output from each of their rails, even after running at full load for an hour. Using a Chroma 6430 power source and Zentech 2100 digital power meter, we then proceeded to measure the PFC efficiency and overall efficiency of each PSU. The FSP proved to be the more environmentally friendly, with an incredible efficiency of 87 per cent, while its PFC circuit was 98 per cent efficient. The Thermaltake won't be quite as popular with David Cameron but, with overall efficiency of 78 per cent and PFC efficiency of 95 per cent, it's a lot greener than a generic ATX PSU.

CONCLUSION

Although both graphics card PSUs were 100 per cent stable at full load, and the FSP was very efficient, only the Thermaltake is worthy of serious consideration. The FSP is noisy, and barely any cheaper than a good-quality 500W ATX PSU, making it poor value for money. The only real limitation of both PSUs is their cooling systems' requirement of a source of cool air at the front; this means that we wouldn't recommend installing one in a case with a front door, or if you did, then you should keep the front door open. If you don't mind this drawback, and don't fancy, or can't afford, a high-wattage ATX PSU, the excellent Thermaltake Pure Power Express will give your PC a whole new lease of life.