ASUS ROG LOKI 850W Platinum SFX PSU Review

ASUS is one of the leading names for high-end PC hardware, with many of the most powerful and feature-packed motherboards, graphics cards, coolers, cases and much more beyond that are available today! However, one thing that we don't get enough of in the eTeknix office has to be their power supplies, which are often some of the best-looking PSUs we've ever seen. Of course, their new RoG LOKI is no exception, this compact SFX unit may be small, but it packs an impressive 850W of power and 80 Plus Platinum Efficiency, and it does it all with some of the most amazing PSU aesthetics you've ever seen, trust me on that one! ASUS ROG LOKI 850W Features Dual Ball Fan Bearings ROG Heatsink Aura Sync | ARGB-illuminated Fan PCI Express 5.0 Ready 80 Plus Platinum Certified Specifications For in-depth features and specifications, please check out the official product page here. Packaging & Accessories The box is obviously quite small, given the PSU is also small, but it's well-designed and durable and has all the usual key information, as well as many photos of the product on the front and back. The cables look amazing, with a paracord glossy sleeving on each individual cable that looks unlike any other stock cable I've ever seen. They are by far the most premium cables I've seen short of a fully custom-made set. A Closer Look Wow, just wow, this PSU comes with a CNC'd aluminium top cover, those silver grooves are deeply cut into the metal and it contrasts greatly with the matte black underneath it. There's even a clear blade fan with plenty of trick RGB effects in there for good measure. Around the sides, there's an ASUS eye log, the wattage, and then just a small Republic of gamer log, which may be RGB lit or just on a glossy plastic, I guess we'll see when I power it up! There's an impressive array of connectors too, with three CPU/PCIe connectors, three peripheral connectors, the motherboard 24-pin, and even the latest 12VHPWR connector. The other side of the PSU looks seriously flashy, with a mirror panel that expands into the eye logo on the right. Even the bottom has that angular design with that specification sticker cut in half to make it look a little less boring. There's a nice ROG logo at the back, which too looks like it's RGB lit, a good amount of ventilation and even a master power switch. The PSU also comes with an ATX adaptor kit should you need to fit it to a larger case for whatever reason. A Closer Look - Internal The top panel is separate from the PSU and can be removed via four small screws. This makes it easy to clean but also makes cleaning that clear fan a little easier. The fan looks stunning, I haven't seen a clear blade fan in a long time, so I'll be eager to see how well this illuminates with the RGB, which often is seen on more milky-coloured fan blades. I won't lie, I am defeated, I couldn't for the life of me figure out how to open this PSU, and I really did try, but it got to the point where I was going to do more harm than good. However, I can see in there, a pair of large capacitors. They're both from Rubycon 420v and the largest is rated at 470 uF, while the other is 330 uF, which is a lot for such a small PSU! All the capacitors in the PSU are rated at 105c. From what I can see, it looks very clean in here, with some large DC-DC converters, and smaller 3.3v and 5v converters on the otherside. There is a very clean-looking AC line-in with filtering and shielding, as well as a range of protections to prevent against brownouts, power spikes and other unwanted phenomena from your power lines. There's a large heatsink running down the MOSFETs, with a cut aluminium design that matches the PSU exterior. There's also a bank of capacitors on the connector board, which will help with voltage stability and ripple. Methodology & Testing At eTeknix we take the power supply testing procedure very seriously and have invested a lot of resources into acquiring the appropriate testing equipment. For all power supply reviews, we test the power supplies with dedicated power supply testing equipment. This means we can get the most accurate results from our testing as opposed to using software benchmarks (such as OCCT) or multi-meter readouts which are broadly inaccurate. Testing Hardware Sunmoon SM-8800 Active Load Tester Stingray DS1M12 USB Oscilloscope Voltcraft DT-10L laser tachometer What the eTeknix Test Procedure Involves Testing each power supply at 20/40/60/80/100% load (with load balanced across all rails) and measuring PFC (power factor correction), efficiency (actual power divided by power "pulled at the wall") which also uses a 50% load test, and voltage regulation (deviance from expected voltages of 3.3/5/12 on the main rails). Measuring ripple with an oscilloscope at 20/40/60/80/100% load. Transient loads taken with an oscilloscope are taken from 0% to 100% on the 12v raid, 3.3v rail, and then both combined. Measuring fan speed after a stabilisation period of five minutes at each loading scenario using the Voltcraft DT-10L laser tachometer and a reflective strip on the fan. Testing each power supply's OPP (Over Power Protection) mechanism and seeing how many watts each power supply can deliver before shutting down. Any deviation from this will be explained per review as appropriate on the respective testing pages, but this methodology page will remain unchanged. Other Things to Consider We recognise that a single 12-volt cable can provide only 6 Amps before overheating (which corrupts voltage regulation and efficiency) so we used an adequate number of cables for each power supply to ensure there is no efficiency loss from poor cable selection. If there is more than one 12VHPWR on a PSU, all will be used to test their combined loads. We use the same time scale and horizontal millivolt scale on our oscilloscope for all ripple tests, that is a 20ms T/DIV (horizontal) and a 0.02 V/DIV (vertical) meaning the scale is from -80mV to +80mV, ATX spec dictates that the 12v rail must fall within 150mv of ripple and the 3.3/5 within 50mv so that scale allows us to include both 150 and 50mV peaks. (Some older PSU reviews use different scales which were later ditched as the visual representation they give is inadequate, in these reviews written measurements are provided only). Deviance is the terminology used to represent the way voltages diverge from the expected values Voltage Regulation To test voltage regulation we load the power supply to five different load scenarios that give an equal spread of load across every single rail. So that means 20% on all rails, 40% on all rails and so on. We then calculate the average deviation of each rail from its expected voltage. Ideally, anything of +/- 2% regulation is seen as a very good result. Power Efficiency Power efficiency is measured by calculating the supplied wattage divided by the wattage drawn at the wall/plug, multiplied by 100 to give a percentage. We then compare that to the particular 80 Plus certification the company claims to see if it meets that. You can see the 80 Plus certifications below, we always test power supplies at 230v. Transient Loads Power Factor Correction Power Factor Correction is the ratio of the real power flowing to the load, to the apparent power in the circuit. PFC aims to make the load circuitry that is power factor corrected appear purely resistive (apparent power equal to real power). In this case, the voltage and current are in phase and the reactive power consumption is zero. The closer the number to one the better as this allows the most efficient delivery of electrical power (Source - Wikipedia). Ripple An oscilloscope can easily measure noise and Ripple. These show how much voltage fluctuation there is on a particular rail. We tested the rail stability of the 3.3-volt, 5-volt and 12-volt rails using an identical time and millivolt scale for all graphs. millivolt ripple is measured by the peak-to-peak size of the voltage curve. The latest ATX 12-volt version 2.3 specifications state that ripple from peak to peak must be no higher than 50 millivolts for the 3.3-volt and 5-volt rails, while the 12-volt rail is allowed up to 120 millivolts peak to peak to stay within specifications. Millivolt figures are stated to the closest increment of 5 given their variability. OPP Power supplies are often quoted as having various protection mechanisms and the most important of these is Over Power Protection. In our testing, we crank up the power draw until the power supply either shuts down (meaning the OPP mechanism is present and working) or blows up (meaning it is either not present or not working). We then note the maximum power consumption before the power supply shut down, or before it blew up. Fan Speed When testing in a power supply laboratory it is difficult to take fan noise readings as the noise from the Sunmoon test equipment and air conditioning corrupts everything. The next best thing in our circumstances was reading off the fan speed with a tachometer to get an idea of the noise. The ambient temperature during testing is held constant at 22 degrees, with 1 degree of variation. Each power supply had a consistent period of 5 minutes to stabilise between each load scenario. In my experience, the following general relationships apply between noise levels and fan speeds, though it can vary greatly between the type of fan used. Below 800 RPM - Inaudible/Silent 800 to 1000 RPM - Barely audible 1000 - 1200 RPM - Audible but still quiet 1200 - 1400 RPM - Moderately noisy 1400 - 1800 RPM - Noisy 1800 - 2000 RPM or above - Intolerable Internal Components This is just an example of what you can expect to see on a PSU interior. Efficiency Efficiency is obviously important, as the better the efficiency, the less power input is required to make the required output. This unit is rated for 80 Plus Platinum and it hit that mark very well, especially at 20-40% loads where it actually sits closer to the Titanium rating, but always stays above 90% throughout all loads, which is exceptionally good. The PFC is excellent too, hitting a sweet spot at around 60-80% load and this is going to result in less heat being generated by the PFC hardware in your most common gaming-type load scenarios too. PFC (Power Factor Correction) Voltage Regulation Voltage regulation is excellent on the 12v rail (split over 3 rails on our load tester, but it is in fact a single rail on the PSU), and on the vital 3.3v and 5vsb rails it has some of the most accurate readouts I've seen to date, very stable, very consistent. Ripple The ripple is really good, I was actually expecting a lot more than this due to the higher power output and the small size of the PSU, but it was very constant on the 12V and the 5V rail. However, for the 3.3 and 5vsb, it was exceptionally low, considering the spec requires it to be under 150mv and were well under 5mv deviance here. 3.3V 5V 12V 5VSB Over Power Protection and Max Wattage This was a surprise, I nearly said shock, but perhaps that's a poor choice of word for a PSU. It's rated at 850W, but those two main bulk capacitors are total overkill, and I was able to pull a staggering 1364 watts from this PSU before the OPP kicked in... holy hell that's a lot of power! Transient Loads These results measure the power supply from 0% load to 100% load on various rails to simulate a power spike from your system. Typically, we would like to see as small a spike as possible relative to the requested voltage. With modern GPUs being notorious for power spikes, this is becoming more relevant in modern PSU design. The specifications for ATX 3.0 were released in February 2022. It includes the new 16-Pin 12vHPWR connector that can deliver up to 600 W to graphics cards. These incorporate data lines for components to negotiate power capabilities with the PSU so they do not draw more power than the PSU is capable of delivering. The specification also has more strict requirements for handling spikes, two times the nominal output for 100 microseconds. Again, absolutely faultless performance, fast, clean and smooth transitions from all the rails. There was a tiny bump on the 12v, but it's so small, it's absolutely nothing of concern, so top marks here. 0-100% 3V 0-100% +5VSB 0-100% 12V Cross-Loads In cross loads, we see very consistent 3.3v rails in both load scenarios, and again in the 5v rail, with only a slight increase in voltage at around 80% load, but we're not even up to 1% deviance here and anything under 3% is regarded as a pass. Fan Speed The fan actually didn't spin at 20% load, the PSU seems to have some always-on passive mode that I wasn't expecting. However, once it did get to temperature at 40% the fan started at 600 RPM, moving to 800 RPM at 60% load and leveling off at 1000 RPM at maximum loads. Overall though, the fan seems surprisingly quiet and quick to react when it's needed. How Much Does it Cost? There's no way to sugarcoat this one, so I'll just tell you the Asus 850W ROG LOKI SFX-L Platinum PSU is £244.99. That's a kick in the butt for sure, but when you consider that smaller PSUs with higher wattages simply cost more than their full-size ATX counterparts, that goes some way to explain the price. However, the higher the efficiency, again that puts the price up, and this is Platinum-rated yet actually runs at near Titanium efficiency levels. Then there's the fact that this has by far, the nicest and most custom-looking cables I've seen on a PSU, add more money for those. Then we get to the addressable AURA RGB fan, the mirror effect sides, the CNC-cut aluminium top plate, the ARGB on the logos, and well... you get what you pay for. Overview The Asus 850W ROG LOKI SFX-L Platinum PSU is far from cheap, but it's far from just a bog standard PSU either. It's an extremely high-quality product in every regard. From the cables to the fan, to the general build quality and aesthetics, money and time have been lavished to make this a power supply you will want to showcase in your next gaming PC... not one you'll simply hide under a PSU shroud. Can you get big wattages in a small form factor for less? Absolutely, you are 100% paying a premium here for the design and the ASUS name, and it's wholly up to you if that's something you're willing to splash out on. If you want something 80 Plus gold and similar wattage, you can save yourself over £100 on something like the Cooler Master V850, a good PSU, but aesthetically it looks like a potato compared to the sparkling diamond that is the ASUS ROG LOKI. And the ASUS one will outperform the Cooler Master in absolutely any of the tests we've done today. The saying goes, you get what you pay for, just be sure you're only paying for what you really want or need. When it comes to performance, it's an absolute beast. The efficiency is superb, meaning it wastes less juice from the wall to power your system, which is great. The fan is quiet, and the design generally has good airflow for its size, so the PSU never felt like it was getting more than a bit warm even at extended high loads. That's likely because our tests show it's capable of putting nearly 60% above its rated 850W, it's totally overbuilt, and that bodes well for those planning to run a high-end gaming PC off of this unit. Should I Buy One? It's small, it's expensive, but it's by far one of the most interesting power supplies I've ever had in the office. From the build quality on the inside to the exquisite craftsmanship of the exterior, and even the cables, everything about this power supply is premium. However, it's not all just for show, as when it's put through its paces, it delivers performance that can rival many high-end ATX PSUs, which is impressive given its more compact form factor.