Our load tests utilize a couple of FAST ATE active load testers and a variety of other equipment such as an oscilloscope, power conditioner, temperature probe and a power consumption meter. You can read more about our standard testing approach here.
The tests performed are based around six conceivable setups that are out there and progressively load down the PSU up to the power supply's limits or 1000W, whichever comes first. Since our test equipment's limits are higher than that of the Corsair RM 850W power supply, we can test it to the maximum.
The above tests represent typical loads that we have measured from various systems and are meant to give a rough idea of where your computer might fall in line with our tests. Please keep in mind that each system is different and actual loads can vary greatly even with similar hardware.
Let's start by taking a look at the voltages to see how well this unit did during testing. Starting with the 12V rail, we see 2% regulation from start to finish with a total drop of .21V. The 5V rail managed to stay within 3% of specification with a total drop of .11V from start to finish. Moving towards the 3.3V rail, we see that regulation was within 3% of specification with a total voltage drop of .10V.
DC Output quality for the Corsair RM 850W was good and well within specifications. During Test 1, we saw 12mV of noise on our scope. When we increased the loads in Test 3, the ripple climbed to 25mV at a little over half load. During Test 5 under a load of 850W, the oscilloscope showed a maximum of 39mV on noise on the 12V rail.
The Corsair RM 850W is rated for 80 PLUS Gold efficiency. This means that the power supply must perform at 87%/90%/87% efficiency at 20%/50%/100% loads respectively. As you can see, the Corsair RM 850W passed on our bench, and wasn't close to failing at any point.
Corsair definitely has a solid hold on the power supply market right now. The AXi series is still almost impossible to beat all the way around and enthusiasts are gobbling them up like crazy. The opposite end of the market is filled by the CM series, which is also selling like hot cakes because it is a quality unit on the very cheap side of things. The RM series resides right in the middle of all of this and brings some of the enthusiast features down to where the average guy can afford them.
On top of this, the RM850 has some solid performance. Voltage regulation is within 3% across the board for all rails. DC output quality is relatively good as well, staying under 40mV at full load. Even the efficiency is spot on for 80 PLUS Gold just as it is rated.
This is all before you factor in the ability to use Corsair Link to monitor your power supply. Throw in the price tag of $150 and you've got a combination of performance and features that that I think is going to be hard for anyone to overcome soon.