Seasonic X-Series 650 W Power Supply Review

Conclusions

What a power supply! What a power supply! For the first time we can say that we found a flawless 650 W power supply. It presents efficiency of 90%, meaning that it consumes less energy from the wall, meaning a lower electricity bill for you. Voltages are within 3% from their nominal values, meaning that they are closer to their “correct” values than allowed (5% is the standard tolerance). And ultra-low ripple and noise levels, which means this power supply won’t overload the capacitors from the voltage regulator circuit from your motherboard or video card and will also prevent you system from producing random errors due to low-quality voltages.

It is always good to remember that we test power supplies at very high temperatures (between 45° C and 50° C). Since efficiency drops with temperature, these results are even more impressive when you think about them, especially because 80 Plus certification is achieved with a room temperature of half of what we used (23° C). We’ve seen power supplies that are 80 Plus Silver or Bronze not being able to deliver the promised efficiency in our labs because of that, what fortunately didn’t happen with X-Series 650 W.

The internal design is also flawless, using only Japanese capacitors rated at 105° C and solid models on the whole secondary. It uses a DC-DC design, which means that it is basically a +12 V power supply with +5 V and +3.3 V outputs being generated from this main +12 V line. This design is being used by several other high-efficiency units, but what makes X-Series completely different is where the components are located. Instead of putting the DC-DC converters on  small daughterboards attached to the secondary, the converters are located on the same printed circuit board from the modular cabling system. This unique design allowed the power supply to have far less cables inside (since only a single +12 V connection between the main printed circuit board and the modular cabling system is necessary), which helps with thermal management and, indirectly, with efficiency (as the higher the temperature, the lower efficiency is).

Speaking of thermal management, the fan of this power supply only kicks in when needed. When the power supply is running with a small load (and thus low temperature), the fan is completely turned off, making the power supply to produce no noise at all.

All semiconductors used on this power supply are highly overspec’ed and this allowed us to pull almost 800 W from this 650 W unit.

And, the best of all: it is not that expensive for an ultra high-end product. The 650 W model costs USD 180 and the 750 W model costs USD 200, and we’ve seen power supplies with far lower construction quality and performance costing more than that.

As a side note, this was the first 80 Plus Gold power supply to reach the market. If you take a look at 80 Plus website you will see a lot of Gold power supplies being listed, however except for Z Series from OCZ all other products being listed there are still on the prototype phase, not available on the market yet.

In summary, if you want the best power supply around, Seasonic X-Series is the product you should buy.