Ultra X4 850 W is a honest power supply, being able to really deliver 850 W at 48º C. The main advantage of this unit is having six separated video card power cables, allowing you to build an SLI/CrossFire system with up to three high-end video cards without the need of using adapters. The high number of SATA (11) and peripheral (nine) power connectors is also an advantage. Its full modular cabling system is a must for users worried about ventilation and cable organization.

Ultra X4 850 W presents very good efficiency when delivering between 40% and 80% from its labeled power (between 340 W and 680 W), on the 83%-85% range. At 20% load (170 W) efficiency dropped to 81.7%, still a decent number. When delivering 850 W, it presented 80.8% efficiency, not the best but still above 80%.

Voltage regulation and ripple/noise were inside specs, although they were not the best we’ve seen around.

Its price is adequate for a product with these features, but we’d like it more if it cost less. Problem is, if you don’t need the modular cabling system you can buy a Seasonic S12D 850 W for USD 180, which provides a better performance (higher efficiency, voltages closer to their nominal values, lower ripple/noise). And if you want a product with a better performance with a modular cabling system you can pay only USD 10 more and get a Seasonic M12D 850 W or an XFX 850 W.