Corsair RM650x (2021) power supply review - Load testing the PSU

Load Testing The PSU

Testing a power supply these days is always a bit of a challenge. I mean, without professional load testers it's pretty hard to stress a power supply of this class and actually measure its behavior.

Our first check is with a simple power supply tester, we monitor voltages quickly and check if all rails are working properly and within spec (spot on perfect actually). It also has a nice self-check immediately indicating it the voltages are at a proper stage.  As you can see, this PSU is spot on.

Load and efficiency testing

For our power supply reviews, we emulate real-world usage and make use of an energy-hungry multi-GPU ready motherboard armed with an accompanying processor. Depending on the power supply wattage we then make use of one or more graphics cards. Older processors and GPUs eat much more power. With power supplies getting so very efficient these days, reaching over 600 Watts actually is a rather hard task to accomplish. Now, on the software side of things, it is time to give the PC a decent beating. Remember, our focus remains on PSU efficiency, not the components we use. We now take some other power supplies and start testing: 

Looking at efficiency is a relatively easy thing to accomplish, gather data. We look at the powered off status (ErP/EuP), productivity mode (we stress the CPUs), and finally, during gaming. The lower the Wattage, the more efficient the PSU, it is that simple. 

Above, a very simple test; once we power down the PC it can still consume power. Following EU legislation your PC and thus PSU and motherboard combo needs to remain under 0.5 Watts in sleep or power-down mode. We measure 0.1 Watts. To achieve this, you will need to enable EuP mode in your motherboard BIOS (!).

Small tip: for those that have and leave RGB bling activated on their motherboard day and night even with the PC powered down, you are using roughly 5 Watts continuously 24/7/365. At 5W that is roughly 44 kWh per year of waste energy and will costs you roughly 10 bucks a year at 23cents/ per kWh.

When we focus solely on CPU productivity mode load for a second we see that the PSU draws 269W, measured on the wall socket side. CPU productivity is video-transcoding, content creation, etc, all your processor's logical cores are 100% at work while your graphics card is doing nothing. 

Probably the best indicator for the Guru3D community, efficient power consumption by looking at a game test. As you can see, the PSU draws 459W from the wall socket. Important to remember is that at 50% load, a PSU is usually at its most efficient. The efficiency value is comparable to other Gold efficiency rated power supplies.