Are you currently thinking of building an SLI enabled Nvidia GeForce 8800 GTX gaming system with an Intel quad-core processor and a couple of hard drives in RAID? Well if you are then you need a 1000 watt power supply right? Wrong, but how can this be wrong with so many 1000 watt power supplies becoming available! In fact you don’t even need an 850 or 800 watt power supply to safely operate such a system. After recently building this exact system we discovered that the maximum power demand created by this configuration was just 530 watts.

Basically we built an Intel Core 2 Extreme QX6700 system with SLI enabled Nvidia GeForce 8800 GTX graphics cards using the ASUS Striker Extreme motherboard and four Seagate 320GB hard drives. Along for the ride were four 1GB DDR2 memory modules and six 120mm case fans as well as a water-cooling system. Even with all this high-end hardware installed we were only able to generate a maximum power demand of 530 watts.

However this does not necessarily mean that a 550 watt power supply will be enough to power an SLI quad-core gaming system, despite the fact that we have successfully done this. Running a power supply so close to maximum load is not a good idea. That said we are yet to run into a problem with this configuration using a 550 watt unit. In fact for two months now the Thermaltake Purepower 550w power supply has powered this gaming system without a single glitch.

Power supply output ratings are actually quite inaccurate and can be very misleading. This is why it is very important to purchase a trusted and respected brand name. The actual wattage output will vary depending on the operating temperature. There is no standard measurement so while one manufacturer can claim an output of 800 watts, this could be at an unrealistic operating temperature such as 20 degrees for example. While another manufacturer might be far more conservative and only claim a 700 watt output at say 40 degrees for example.

So as you can see, there can be a very big difference between a 550 watt power supply that can really handle a 550 watt power load and a power supply that is simply rated at 550 watts. Therefore it really is important to focus more on the quality of the power supply rather than the “claimed” power output. This can be hard to do, but the main thing to do is stick with the trusted names and go more by a certain price range than a power output. Everything we are going to talk about in this article really comes down to quality.