It is well-known among PC enthusiasts that most hardware companies that sell PSUs do not actually manufacture their products. Instead, they rely on platforms and designs developed and manufactured by the Original Design Manufacturer (ODM). The engineers employed by the various client-brands do perform modifications and/or upgrades to the original design but, more frequently than not, these modifications are limited to aesthetic modifications and the use of a different fan. All of which means that many of these ODM-derived PSU designs are essentially copies of the original platform’s topology and recommended electronic components. In other words, while there are dozens of PSU vendors out there, the PSU industry as a whole is built on the back of a handful of companies.

Over the past decade, several ODMs decided to launch their own retail divisions. The most prominent examples are SeaSonic and FSP Group, whom release new retail products almost every time they upgrade their core designs. FSP Group recently performed a long-overdue update of their retail lineup and presented several fresh products. A few months ago we had a look at their top-end Hydro PTM Pro 1200W ATX PSU, an upgraded version of their tried & true flagship platform that has been around for nearly a decade. In today’s review, we are going to have a look at something significantly different – a very powerful 850W SFX unit, the Dagger Pro.

By traditional metrics, 850 Watts is a lot for a typical small form factor (SFF) PC, but the constantly growing demand for compact--yet-powerful PCs is continuing to drive increasing demand for high-performance SFX PSUs. This is caused primarily by the gaming market, as top-tier graphics cards have substantial power requirements (e.g. 450W for RTX 3090 Ti). On paper, the FSP Dagger Pro 850W is not too impressive by today’s standards, with an 80Plus Gold certification and no extravagant features – but it makes up for that with its tiny dimensions.

Packaging and Bundle

We received the FSP Dagger Pro inside a relatively large and very sturdy cardboard box that one could easily assume was meant for an ATX unit instead. Inside the box, the small PSU lies inside a very thick packaging foam container. The artwork may be a little excessive but is not really extravagant, with plenty of information printed on all sides of the box.

FSP kept the bundle fairly basic, with just a regular AC power cable, typical mounting screws, and a small manual to be found inside the box. The noteworthy addition to the bundle is the SFX to ATX adapter that allows the Dagger to be installed in ATX-compliant cases, allowing users the flexibility to switch between ATX and SFX cases at will.

With the Dagger Pro being a fully modular PSU, every cable can be detached. This includes the main 24-pin ATX cable. All of the cables are ribbon-like, “flat” type, with black wires and connectors. It is noteworthy to mention that the cables with the SATA and Molex connectors are mixed.

The FSP Dagger Pro 850W SFX PSU

External Appearance

Despite the massive power output of the unit, FSP’s engineers somehow managed to maintain the standard SFX form factor dimensions of 125 × 63.5 × 100 mm / 4.92 × 2.5 × 3.94 in (W×H×D), making the Dagger Pro fully compatible with any SFX-compliant case. The chassis of the Dagger Pro is sprayed with textured black paint.

Stickers with the company and series logos cover both the left and the right side of the chassis. The top side is covered by the sticker with the electrical specifications and certifications of the unit.

One of the major setbacks that SFX PSUs have is that 120 mm fans do not fit into the standard SFX form factor dimensions. As such, FSP had to use a slim 92 mm fan for the Dagger Pro. Regardless, despite the very compact dimensions, FSP somehow managed to place a small on/off switch next to the AC cable receptacle on the rear side of the PSU.

The front side of the Dagger Pro is home to the connectors for the modular cables. A subtle legend is printed on the chassis itself, in the same gold color as the rest of the artwork. The connectors are keyed, so it is not possible to insert any cable into the wrong connector.

Internal Design

The 92 mm low profile fan responsible for the cooling of the Dagger Pro 850W is supplied by Power Logic, a relatively well-known fan manufacturer whose products are frequently found on GPU coolers. It features a simple but very reliable double-ball bearing engine and has a maximum rotational speed of 2500 RPM.

Naturally, there is no third-party ODM behind the creation of the Dagger Pro as FSP designed and built this unit themselves. The interior of the unit is clean but packed to the brim, with the designers clearly having spent many hours trying to make everything fit inside standard SFX proportions. The filtering stage begins at the rear of the AC receptacle and extends over the side of the chassis, with two Y capacitors, two X capacitors, and three filtering inductors total. There are two rectifying bridges that are simply attached to each other, without any heatsink cooling them.

Due to size restrictions, the designers were forced to use three APFC capacitors, the combined total capacitance of which is 420 uF. All three capacitors are supplied by Nippon Chemi-Con. There are two primary side inversion MOSFETs that form the heart of a half-bridge design, feeding a rather small unique transformer.

The secondary side MOSFETs are placed underneath the main PCB and are thermally connected to the chassis of the PSU. This is a common technique in such very compact designs. A vertical PCB on the side of the unit holds the DC-to-DC converters for the 5V and 3.3V voltage lines. Nippon Chemi-Con and Rubycon supply the electrolytic capacitors, while the polymer capacitors are coming from Teapo.

Cold Test Results (~25°C Ambient)

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 efficiency of the FSP Dagger Pro 850W unit does meet the 80Plus Gold certification when the unit is powered from a 115 VAC source. Powering the PSU from a 230 VAC outlet will result in a slightly better overall efficiency, especially under heavy loads, but the figures are well below the 80Plus Gold certification limits. It has an average nominal load efficiency of 91.8% when powered from a 230 VAC source, which drops down to 91% if powered from a 115 VAC source.

FSP implemented a “hybrid” fan controller that allows for the fan to completely stop when the load is low. Unlike other implementations, it is not possible to turn this feature off. As expected, the internal temperatures of the PSU rise sharply under low loads due to the lack of active cooling but quickly stabilize once the fan starts. Due to the mediocre efficiency and very compact size of the unit, its internal temperatures are relatively high.

The use of a low-profile 92 mm fan inside such a compact unit with significant thermal losses did have the expected side effect of high audible sound pressure levels. The fan will not start when the load is low but does start the moment the load is greater than 200 Watts. Once the fan starts, it quickly becomes clearly audible, with the noise staying within relatively comfortable boundaries up to about 500 Watts.

Hot Test Results (~45°C Ambient)

Despite its small proportions and significant thermal losses, the energy conversion efficiency of the FSP Dagger Pro 850W PSU does not degrade significantly across most of the load range when it operates in a high-temperature environment. The average efficiency reduction is less than 1.1%. However, there is a very significant degradation when the load is greater than 750 Watts which reaches up to 3.6% at maximum capacity, suggesting high thermal stress.

Despite the high ambient temperature, the 92 mm cooling fan started only a little bit sooner while the Dagger Pro was operating inside our hotbox. Noise levels initially are low but the speed of the fan climbs up quickly as the load increases, reaching clearly audible figures when the load is less than 300 Watts. Ultimately, the fan reaches and maintains its maximum speed, producing noise that would trouble even the most tolerant of users.

The small proportions and significant thermal losses of the Dagger Pro, combined with the low-profile 92 mm fan, result in very high internal temperatures when the ambient temperature is very high. Once the load is greater than 600 Watts, the fan and the heatsinks seem no longer able to cope with the thermal load and the temperature begins rising sharply and well over 100 °C. We also failed to trigger an over temperature protection (OTP) shutdown, meaning that FSP’s engineers probably have the limit set exceedingly high.

Power Supply Quality

As part of our testing, we also check output parameters are within specifications, as well as voltage ripple and line noise.

Most early SFX PSU designs displayed poor power quality figures but, thankfully, all recently released platforms have been greatly improved. The only peculiar characteristic of the FSP Dagger Pro is that the power quality worsens when the load goes below 200 Watts, quite possibly an unforeseen side effect of operating with passive cooling. Regardless, the power quality figures are very good across the entire load range, with the voltage ripple figures below 50% of the recommended design limit. Voltage regulation is equally good, with the 12V maintaining regulation of 0.8% across the nominal load range, which figure goes up to 1.2% for the 3.3V and 5V lines.

As part of our standard testing, we test the primary protections of all PSUs we review (Over Current, Over Voltage, Over Power, and Short Circuit). The FSP Dagger Pro 850W successfully passed all of the tests, generally reacting timely when needed and shutting down to protect itself and the components it is powering. It is noteworthy to mention that the over-power protection (OPP) is set quite low, with the unit shutting down in less than a second when the load is set at 900 Watts. Considering the design and nature of the unit, having the OPP limit set low probably is a good thing for the longevity of the unit itself.

Conclusion

FSP recently updated almost every platform they use in FSP-branded PSUs, and the SFX Dagger Pro series was no exception. With its very compact proportions and massive power output, it is clear that the firm wants to make a serious move towards enthusiasts who build compact but very powerful gaming PCs – a small and yet significant piece of the market.

Not too long ago, it would seem unfathomable for any designer to fit that much power in standard SFX proportions and still keep the cost low enough that the product would be viable for retail store shelves. The inside of the new Dagger Pro 850W PSU definitely is congested but, without question, the firm’s engineers managed to create a clean and workable design. However, sacrifices had to be made in order to fit that much power output in such compact proportions.

The quality of the new Dagger Pro 850W PSU is unquestionably great. It is a well-made unit and the firm is only using top quality components, even for secondary parts. One could argue that they probably had no choice, else the density of the unit itself would threaten its long-term reliability. Regardless, the fact is that the company currently backs the Dagger Pro 850W PSU with a massive ten-year manufacturer’s warranty, underscoring that the PSU is meant to last.

When the Dagger Pro 850W PSU operates under reasonable conditions, its overall performance is good. We received great power quality figures, with exceptional voltage regulation and good filtering. The efficiency is not stellar by today’s standards but does meet the advertised 80Plus Gold certification limits. The combination of extreme power density and the small 92 mm fan did hint at mediocre thermal performance, and that was what we got, with the Dagger Pro getting hot and significantly loud under stress. However, it did not fail to deliver its full power output – not even while it was operating inside our hotbox.

High performance SFX PSUs are slowly but surely gaining ground on the PC market. There are few very powerful SFX units that have two 12V CPU connectors and four PCIe connectors, and as a result there are few direct competitors to the Dagger Pro. On the other hand, enthusiasts who will be building a very compact gaming PC that needs four PCIe power connectors are also very few, meaning that the Dagger Pro is primarily targeted towards a niche market.

Ultimately, with retail prices typically hovering at around $180, the Dagger Pro 850W is priced relatively reasonably given the very high power output of the PSU. Still, it's worth noting that 750W SFX PSUs, including the 750W version of the Dagger Pro, often retail for $30 less and can still power exceptional gaming PCs. So while the 850W version is easy enough to recommend for users who truly need the awesome power of an 850W unit, for most ITX/SFF gaming builds 750W models are a more than reasonable choice that also saves some money in the process.