Introduction

SilverStone is one of the most reputable PC chassis and PSU manufacturers worldwide. The company is no stranger to AnandTech as we reviewed a plethora of their products during the years. However, it has been a long time since we reviewed one of their high-end power supply units; as a matter of fact, ever since the review of the Zeus 1200W PSU seven years ago, we have only been reviewing their least powerful PSU models. As a result, SilverStone supplied us with their currently most powerful model - the Strider Gold S 1500W (ST1500-GS).

SilverStone has some very interesting things to say about the Strider Gold S 1500W PSU. These include the fully modular design, 80Plus Gold certified, compact design, strict performance standards and a frightening price tag of $350. However, what is even more terrifying is that it has been rated for continuous operation at 40°C, not 50°C like the majority of manufacturers do for their high-end models. This is not in any way illegitimate as this is the normal rating for the operating temperature of consumer PSUs and other companies do rate some of their units at 40°C as well. However, a $350 PSU rated at 40°C comes with an element of shock, especially when considering our recent review units which have also had a 40ºC limit. 

Packaging and Bundle

The packaging of the Strider Gold S 1500W PSU is modest and sturdy, with a wealth of information to be found on the sides and the back of the box. The artwork is dark and very simple, as SilverStone always prefers focusing their efforts on beautifying the product itself. Inside the box, the PSU is protected very well within a polyethylene foam shell and a nylon bag.

SilverStone provides a good bundle with the ST1500-GS, consisting of a good manual, an AC power cable, a nylon fan filter guard, a few cable ties, four long cable straps and two sets of black screws (one normal set and one set of thumbscrews). The fan filter is magnetic but it can also be screwed in place if necessary.

We should note that the AC power cable included this PSU is not a standard C13 plug but a C19 plug, as shown on the unit below.

The ST1500-GS is a fully modular PSU, down to the ATX 24-pin cable. Every cable is a sleeveless, flat "ribbon" type, made using all black wires and connectors. This includes the ATX cable and the CPU/PCI-E 12V connectors. Only the blue connectors at the PSU side of the PCI Express power cables stand out against the vantablack-like design. The ATX cable also has a 4-pin voltage sensing connector that needs to be connected to the PSU separately.

External Appearance

SilverStone was not kidding when they said that this is the world's smallest 1500W power supply. The 180mm chassis is certainly not adhering to standard ATX specifications, yet it is significantly shorter than any 1500W power supply we have seen to date. With its modular design and a short cable kit available, SilverStone mentions that someone could even install this in some HTPC and small form factor cases, and even recommends some of their HTPC cases for use with the ST1500-GS. We cannot possibly fathom why anyone would want to power any such system with this behemoth, but the possibility is there.

The chassis is sprayed with a grainy black paint that is smudge and scratch resistant. SilverStone attempted to engrave the whole company logo across the top of the chassis, somewhat unsuccessfully, as it is barely visible to the naked eye in a well-lit environment.

A metallic badge with the company logo can also be seen at the center of the fan finger guard. The sticker with the electrical specifications of the PSU is on the left side of the chassis, visible from a windowed side panel if the PSU is installed with its fan facing downwards.

The only interesting thing at the rear of the PSU is the lack of a simple on/off switch. Apparently, certain sacrifices need to be made when trying to fit that much power in a 180mm long chassis. The numerous connectors for the modular cables can be seen at the front of the chassis, with a sticker indicating which connector corresponds to each cable. SilverStone also placed small plastic caps on the connectors, which is definitely more of an aesthetic than a practical enhancement.

The CPU and PCI Express cables do not share the same connectors, which differ in color. These are also keyed, meaning that you cannot insert either cable into the wrong connector, even if they both have the same number of pins. The 24-pin ATX cable has a little connector beneath it for the voltage sensing connector, which is oddly recessed almost half a centimeter inside the body of the unit. The smaller connectors are for SATA/Molex cables.

Internal Design

A standard black 135mm fan from Young Lin Tech is what lies beneath this unit's circular finger guard. The model of the fan is DFB132512H, which means a dual ball bearing system and a maximum speed of 2500RPM. Such a speed is insanely high for a 135mm fan, which would be pushing over 120CFM if it were to reach it. As with any modern PSU, the ST1500-GS features thermal control circuitry adjusts the speed of the fan according to the load and the temperature of the unit; we can only hope that it will not get anywhere near its maximum speed.

For the creation of the ST1500-GS, SilverStone enlisted a not very well known but respectable OEM - Enhance. The layout is extremely well designed, especially considering the vast number of components that the designer had to fit in such a small chassis. Many PSU layouts are a mess with half as many parts. The designer certainly did not hold back either; even though this is a 1.5kW top-tier PSU, everything about it is an overkill. The filtering stage comprises of four Y capacitors, four X capacitors and two filtering inductors. There are two NTC thermistors to limit the inrush current, which would be immense considering the size of the capacitors, with a relay for each. The relays will isolate the thermistors after their job is done, minimizing energy losses. The primary conversion bridges share their own small heatsink right after the filtering stage.

Despite its appearance, the huge heatsink along the side of the PSU only holds the Active PFC chips, three transistors and a diode. The passive components of the PFC circuit are a large filtering inductor and not one, not two, but four Matsushita (Panasonic) 270μF/420V capacitors. Without the NTC thermistors, the inrush current of this PSU would probably be high enough to de-solder or even melt wires. A simple, plain heatsink that looks like nothing more than a metallic plate holds all four transistors of the primary inversion stage, which form a full-bridge configuration.

The secondary conversion stage transistors are at the bottom of the main PCB, on a thermal pad. SilverStone is cleverly using the body of the unit itself as a heatsink for the secondary side, which will normally get (very) warm if the PSU is loaded. This however will also have a side effect that we cannot quantitatively assess within the frame of this review - it will increase the internal temperature of the system that will be powered by this PSU.

The quality of the Strider Gold S is a very complicated matter. As we mentioned above, the PFC stage electrolytic capacitors are supplied by Panasonic. Most of the secondary stage electrolytics are supplied by Nippon Chemi-Con and Rubycon, both of which are very reputable companies. There, unexpectedly, a TAICON electrolytic capacitor appears. TAICON is a good manufacturer as well but the company does not share the reputation of either Nippon Chemi-Con or Rubycon. Still, the role of that capacitor is not highly important, nor it is installed in an area that is expected to get overly hot. The polymer capacitors are supplied by Teapo, which SilverStone selected because these are almost impossible to fail regardless of the manufacturer.

It also may be exceptionally well designed, but on balance the assembly quality is mediocre. The soldering job is messy, with copper wires dipped in solder serving as power rails (see above) and numerous joints that look as if they have been manually performed by a complete amateur, which comes across as a little worrying. 

Cold Test Results

For the testing of PSUs, we are using high precision electronic loads with a maximum power draw of 2700 Watts, a Rigol DS5042M  40 MHz oscilloscope, an Extech 380803 power analyzer, two high precision UNI-T UT-325 digital thermometers, an Extech HD600 SPL meter, a self-designed hotbox and various other bits and parts. For a thorough explanation of our testing methodology and more details on our equipment, please refer to our How We Test PSUs - 2014 Pipeline post.

The SilverStone Strider Gold S 1500W met its 80Plus Gold conversion efficiency requirements, even if only barely. We recorded a maximum conversion efficiency of 90% at 50% load and an average of 90.0% within the nominal load range (20% to 100% of the unit's capacity). Low load performance is mediocre, with the ST1500-GS maintaining an efficiency of 80% at 10% load, which drops to 74.4% at just 5% load. These are actually good figures considering the size of the power supply, yet they are nothing special by today's standards.

Always considering its massive power output, the ST1500-GS maintains very low internal temperatures. The primary heatsink of the PSU barely reached 67°C under maximum load, when the four transistors were pumping more than 1.5kW to the main transformer. This can be partially attributed to the "stepping" behavior of the cooling fan. While the load is low, the fan is barely audible when unobstructed, meaning that it would be virtually imperceptible with the PSU installed inside a case. At 55%-60% load, the speed of the fan steps up and the fan becomes audible, yet the noise output remains within comfortable limits. If the load exceeds 70% of the unit's capacity, then the fan speed steps up again, making the fan clearly audible and clearly prioritizing thermal performance over acoustics.

Hot Test Results

As it can be seen in the following tables, SilverStone's currently most powerful PSU does offer outstanding power quality, especially if the massive power output is taken into account. The maximum voltage ripple on the 12V line is just 30mV at maximum load, under an outrageous current draw of nearly 110A. Ripple suppression is equally great on the minor voltage lines as well. Voltage regulation is a little more complicated, as the stability of the 12V line is amazing, with a change of less than 1% across the load range. However, the regulation of the 3.3V/5V lines is a lot less tight, at 2%/2.4% respectively.

Once again, we need to mention that this is a PSU rated at 40°C and we perform our testing at temperatures higher than 45°C - we could reduce the ambient temperature of our hotbox testing but we chose not to do so as the results would then not be comparable to those of our previous reviews.

According to these results, it becomes apparent that SilverStone is most likely just playing it safe regarding the 40°C rating for continuous operation. High ambient temperatures had little effect on the performance of the ST1500-GS, reducing its energy conversion efficiency by an average of just 0.3%. The maximum efficiency is reduced to 91.6% at exactly half load.

High temperatures are to be expected from a PSU with this kind of power output and the ST1500-GS does get terribly warm when fully loaded under these conditions. Do note however that the probe that is taking our secondary side readings is now sandwiched between the thermal pad and the chassis (that acts as the main secondary side heatsink), meaning that the readings are naturally higher than with other models. The cooling fan once again follows a "stepping" speed model - the only difference is that now the fan jumps up to maximum RPM at 90% load, correctly abandoning every notion of acoustic comfort to ensure reliability. 

Conclusion

The Strider Gold S 1500W may not be the most advanced but it is the most powerful PSU SilverStone currently offers. SilverStone is a company that designs and produces many non-standard cases for HTPC and SFF systems, therefore having a PSU with massive external proportions in their product ranks would not offer the correct synergy. The ST1500-GS is "only" 180mm long - longer than a standard ATX PSU but much more compact than the majority of equally powerful units. However, compactness alone is not enough to win in this segment of the market. Such power is unnecessary for typical HTPC, living room gaming and SFF systems. Virtually no enthusiast would purchase a 1.5kW unit for its external proportions alone and an extremely small number of users would even attempt to compress a system that requires this level of power inside a small chassis.

Regardless of its proportions, the ST1500-GS does match the competition in both quality and performance. The designer of this unit did an outstanding job with the layout, creating a compact and yet a very clean and powerful platform. Despite its relatively small size, they do not cut corners by removing filtering components or using smaller heatsinks. The only exception is the lack of an on/off switch, which would be of considerable size in order to hold such a large input current and apparently the designer decided not to install one at all. SilverStone is using high quality components as well, all coming from very reputable manufacturers. Albeit crude, the assembly quality certainly has room for improvement but it does not cause reliability concerns. Strangely, the warranty period of this unit is, at the very least, unclear. There is no mention of the warranty length on the box or in the web page of the PSU. Only the manual mentions, "Most SilverStone PSUs are covered by a 3 year warranty. For some models the warranty may vary from 1 to 5 years (North America) or 2 to 5 years (EU)". The warranty period should be clearly mentioned on the packaging and online.

In terms of performance, the ST1500-GS does not break any records but does very good overall. It is strange that SilverStone rates this unit for operation at 40°C, as it proved capable of delivering its promised power and performance at much higher temperatures without issues. Most likely, SilverStone is playing it safe, as the power output of this PSU is massive, its proportions are compact and some people may actually install it inside a case not exactly suitable for such monstrous systems. The energy conversion efficiency is good and resists high temperatures well, while the power quality remains excellent even when the internal temperatures of the PSU are very high. As the company promises, the ST1500-GS is also fairly quiet - at least while it is not heavily loaded. This should please the majority of the users, as everyone want their systems to be comfortable when performing casual tasks, such as web browsing or watching a movie, but few would even notice the noise of the system while gaming.

In conclusion, the SilverStone Strider Gold S 1500W is not only compact but also is a high quality PSU that performs very well overall. The ST1500-GS has only one true enemy - its own price tag. With a retail price of $350 including shipping at the time of this review, it is one of the most expensive consumer PSUs in existence. There are several other high performance 1500W PSUs that are considerably cheaper and excellent 1200W PSUs may be purchased for nearly half the price. Even though it truly is a very good product, the price tag of the Strider Gold S 1500W PSU is unquestionably going to limit its sales.