XFX XTS 520W Passive Modular Power Supply Review

Introduction & Packaging For PC users who are serious about noise there really is no alternative to a passive power supply. Sure there are power supplies on the market that operate incredibly quietly (such as Be Quiet's Dark Power Pro range) and even power supplies that don't spin up their fans until they pass a certain load amount, normally 40% load (Corsair's AXi range for example). However, a fan is still a fan whichever way you butter it up and a fan means some noise irrelevant of how quiet that fan is. Enter XFX's latest passive range of power supplies dubbed the XTS series. Today we are checking out the XFX XTS 520 which is a totally silent, passively cooled 520W power supply with a fully modular design, 80 Plus Platinum certification and a 5 year warranty. This really is the bees knees of power supplies and while 520W may not sound like much, that's easily enough to power a Core i7 4960X system with a GTX Titan Black and a tonne of hard drives or SSDs, lots of memory and a full sized ATX board. With that said the XFX XTS 520 is a power supply that is versatile enough for any system from a low-end workstation to a high-end gaming PC: you can even run SLI or CrossFire with this power supply. As with all XFX power supplies the XTS 520 is based on a Seasonic OEM design: this means it is going to be a quality piece because Seasonic are one of the top vendors in the entire power supply industry. Let's start this review by taking a look at the packaging of XFX's XTS 520. Packaging and Contents The packaging features images of the product as well as all the relevant certifications of SLI, CrossFire, 80 Plus Platinum and the fact it is Haswell C6/C7 low power state ready. Moving around to the back and we find that the packaging details more features about the power supply. XFX note the use high quality 105 degrees celsius rated Japanese capacitors which is always nice to see and reassures you about the quality of the product. Included with the power supply is a brief user manual, four silver screws for securing into your case and an EU-style power plug. We expect that the power plug will reflect the region within which you buy the product (unless the retailer you buy from is selling imported stock from other regions). A Closer Look - Exterior Power Supply Unit Being a passive unit the top of the power supply has to be opened up for ventilation. You must face your power supply this way up to ensure that heat can rise upwards into your case to be carried out by the airflow of your case fans. I would not advise mounting this PSU in a top-mounted case if you can help it. The bottom of the power supply offers up the rail and wattage breakdown and we can also see more ventilation ports which are essential for keeping this passive unit cool. The side features the XTX XTS branding as well as additional ventilation ports. The other side has the same branding in reverse and a slightly smaller ventilation area. This PSU is fully modular so all cables are detached. You can also see we've got even more ventilation areas on the front too! Round the back we have the standard kettle lead input and a simple on/off switch, and yep, you guessed it - more ventilation. Cabling The included cables are all made of black wires with the motherboard cable also getting sleeving. These cables will be great for keeping things neat and tidy. You get one motherboard 24pin cable and two CPU 8 pin cables of which one is a standard 8 pin and the other is a 4+4pin. For graphics cards there are two PCI express cables but they are based on daisy-chain connectors, however, there are four connectors on offer so you can run two dual-power connector GPUs like SLI GTX 760s or Crossfire R9 270Xs. The other cables for SATA, molex and FDD are offered in five cables. The first cable (moving left to right) has four molex and one FDD connector, the next cable has two SATA, the next has two molex, the next has two SATA and the last cable has four SATA. A Closer Look - Interior Internally this unit is based on Seasonic's Platinum 520W power supply. This is a great OEM layout that is clean, well-built and uses high quality components. Seasonic's design uses 105 degree rated Japanese capacitors for regulation (the small red ones) and a large Hitachi 420V 330 uF hold-up cap which is also rated for 105 degrees celsius (that's the blue one). There are abundant heatsinks throughout the power supply to ensure that heat is effectively dissipated in passive ways. For those interested in a more detailed and technical component analysis you can find that here. Test Procedure 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 are able to 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. Our test machinery is as follows: Sunmoon SM-5500ATE Active Load Tester (1200W rated) Sunmoon SM-268 Active Load Tester (450W rated) GW Instek GPM-8212 Digital Power Meter Stingray DS1M12 USB Oscilloscope Voltcraft DT-10L laser tachometer The eTeknix test procedure involves: Testing each power supply at 20/40/60/80/100% load (with balanced load across all rails) and measuring PFC (power factor correction), efficiency (actual power divided by power "pulled at the wall") 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. Measuring fan speed after a stabilisation period of five minutes at each load 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 Other things to consider are that We recognise that a single yellow 12 volt cable can provide only 6 Amps before overheating (which corrupts voltage regulation and efficiency) and so we used an adequate number of cables for each power supply to ensure there is not efficiency loss from poor cables selection Our Sunmoon SM-5500ATE power supply tester is not capable of testing more than 300W on each of the 12 volt rails so where a power supply provides more than 300W on a 12 volt rail that power is distributed over multiple 12 volt rails on the load tester. For example a power supply with one 12 volt rail supplying 750 watts would be spread equally over three 12 volt rails on the load tester, a power supply with two 450W 12v rails would be spread over four 12v rails on the load tester, two 225W 12v rails for each of the 12v rails on the unit. 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 Efficiency, PFC and Voltage Regulation 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 deviance of each rail from its expected voltage. Power Efficiency Power efficiency is measured by calculating actual 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 230v power supplies. Power Factor Correction Power Factor Correction is the ratio of the real power flowing to the load, to the apparent power in the circuit. The aim of PFC is 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 Noise and Ripple can easily be measured by an oscilloscope. 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. Load (%) 3.3V Ripple 5V Ripple 12V Ripple 20 10mV 10mV 20mV 40 10mV 10mV 25mV 60 10mV 15mV 25mV 80 10mV 15mV 30mV 100 15mV 15mV 30mV Over Power Protection and Max Wattage Power supplies often quote as having various protection mechanisms such 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 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 for the noise. The ambient temperature during testing held constant at 22 degrees, with 1 degree of variation. Each power supply had a consistent time 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 RPM or higher - Intolerable Final Thoughts Pricing XFX's XTS 520 will be coming to the UK market with an MSRP of around £107 from what we have heard. That translates to a U.S MSRP of about $140. This power supply comes with a 5 year warranty. Conclusion The testing results reveal that the XFX XTS 520 is a truly top-notch power supply. It boasts impressive ripple suppression, total silence and very strong voltage regulation across all the rails including the minor ones that other PSU vendors often skimp on. The fully modular design is also very nice and the fact the cables that are provided are all black mean this is one of the tidiest and easiest power supplies to build with. Of course you have to pay a premium for this unit, around twice what you'd pay for a high quality modular 500W PSU from other vendors but you do get the benefits of passive operation and high quality components that provide 80 Plus Platinum efficiency. XFX have also modified the original Seasonic OEM design to offer a smarter choice of cables: it now includes four PCIe connectors meaning you can easily support SLI and CrossFire of mid-range graphics cards like GTX 660/760s or R9 270Xs/HD 7870s. On the down-side, as we've already mentioned, the price is a little high. We also note that the XFX unit has 2 years less warranty than the Seasonic OEM design it is built from although XFX are offering more competitive pricing and better cable options such as the four PCIe connectors instead of two and the fact the FDD connector is now combined onto a molex strand not provided in a separate adapter cable. The unit has slightly below-par PFC performance at lower load scenarios than other units of a similar wattage that I've seen, but that problem soon fizzles out once you start hitting load scenarios upwards of 40%. Pros High quality components Silent operation Excellent voltage regulation 5 year warranty Great cables Cons Mediocre PFC at 20% load Pricey for a 500~W unit No included cable ties "If silence matters to you but you still want a quality power supply capable of powering a decent spec system then the XFX XTS 520 is a great power supply to consider. Built from a rock-solid design with the highest quality components, a fully modular design and an impressive warranty you'll be hard pressed to find anything better for the price that is also passive." Thank you to XFX for providing this review sample.