Introduction

Not long ago we started our power supply reviews with the Silverstone Olympia OP650. Today we will be looking at the Decathlon series which is in fact the same power supply from the inside. The only difference is that the Decathlon has modular cables.


As we saw with the Silverstone OP650 the build quality of this power supply is very good and we expect to see a very high efficiency rating as well. As both the Olympia and Decathlon use the same basic design, we are once again dealing with a single 12V rail on this PSU. We have mentioned in previous reviews that we are not entirely in agreement with companies that deal this approach is best -- standards exist for a reason.

It might theoretically improve compatibility with some higher-end graphics cards, but it also increases the risk of damage to the system and it can be dangerous for the end-user as well. Keep in mind that all graphics cards also have to follow standards, so if a single 12V rail that follows the Power Supply Design Guide is unable to deliver enough power to a certain graphics card, the card manufacturer should be reworking the design rather than expecting other companies to break with standards in order to support their card.


Just like the Olympia the Decathlon is manufactured in Taiwan. In fact since it is the same PCB with the same components it uses the same production line and only comes in a different housing. The label shows the same data as the Olympia 650W.



Packaging and Appearance




Since we have a cable management with the Decathlon we found a bag in the box which can be used to store cables that aren't needed at the moment. It also comes with the standard power cord and screws in the box. The DA650 is much longer than the OP650. The reason for this will be easy to see once we open the PSU up. The whole backside has been punched with small hex-shape holes for ventilation purposes.




On the side are two white stickers informing owners that the warranty will be voided if they're broken. We have taken the liberty of voiding our warranty so you don't have to. Behind the one sticker is a potentiometer and the other one covers a little switch. According to Silverstone the switch is there to combine the four 12V rails into one. Meaning that with that switch they just turn off the OCP for each rail and (hopefully) have a bigger OCP (Over Current Protection) circuit kick in.



Cables, Connectors, and Fan




As we know from previous experience, Silverstone likes to attach all the cables to the PSU before shipping. The Decathlon DA650 is no different. The cable harnesses are sleeved up to the first connector. After the first connector, the cables are left blank without even cable ties. The jacks are located on the upper half of the front side of the PSU. Below the jacks is a little graphic that shows each jack with the appropriate connector name. With all the cables disconnected you can see how Silverstone installed the PCB for the cable management system into the power supply. All the jacks are just sticking out of a big punched hole.


The Decathlon provides enough cables and connectors for just about any situation. The length of up to 105cm will reach any component even in larger cases. The distance between each plug can be a little bit too long, however. If you have two hard drives above one another and you use only one cable then you will have to fit the extra 25cm of cable somewhere in between. Several shorter distances between connectors would be appreciated, allowing the end user to select the cable that's best for their particular setup and thus avoid making a cable salad - after all, that's the purpose of using modular cables in the first place.



The fan guard of the 12cm fan is embedded in the housing of the power supply which is good for cases that do not have enough space for the added bulge. The fan itself is different from the one in the Olympia OP650. This one is manufactured by Adda and rated at 0.50A. The differences between the two fans can clearly be seen in the fan speed and acoustic testing.



Internals - Primary Side


The inside looks almost exactly the same as the Olympia series, with the only significant difference being the length of the housing. The reason for the extra length is pretty clear: Silverstone needed to attach all the cables to the PCB that has the cable management sockets, and in order to accommodate this PCB they needed a bit more space. The above shot also shows how much smaller the secondary heatsink is than the primary. We mentioned this in our Olympia OP650 review and it clearly shows in the temperature results.



We can also see the high quality construction that comes from Silverstone's robot operated production line in Taiwan. Starting at the back of the unit where air is exhausted, we find the usual transient filtering stage with all the expected components. On the far left side attached to the secondary heatsink we can see the rectifying bridge that converts AC to DC current.


The primary side shows nothing unusual. Here we have the three main 150µF capacitors manufactured by Hitachi, as we saw with the Olympia. They are small enough to fit under the primary heatsink. This is a good idea since it allows the heatsink to be larger, and the larger the heatsink the better the resulting temperatures. The extra length creates more surface area which also helps to dissipate heat better.



Transformers and Secondary Side


Somewhat unusual, and just like the Olympia OP650, the Decathlon DA650 has two main transformers. Both run in tandem to provide all rails simultaneously. Other manufacturers use the first transformer to power one rail along with the secondary transformer, which then powers the remaining rails.


The PCB that houses the jacks for the modular cable sockets looks very clean from the back. Silverstone attached all the DC outputs to this PCB, so having a high quality design is important for providing clean transfers. We have seen cable management PCBs that look a lot worse from other manufacturers, for example those from Andyson.



The secondary side shows similar quality. The cables are neatly attached to the board and the PCB has enough space so that it doesn't get bent or torqued. The smaller PCB includes the OCP protection features, the PWM control, and the fan speed control.



It's a pity that Silverstone's engineers had to cut off such a big piece from the secondary heatsink, since as we will see its performance is clearly not as good as the primary heatsink. Not only is it shorter but half of the horizontal fins are also cut off, resulting in greatly reduced surface area. The cables are nicely connected to the modular PCB, but we're a bit surprised that Silverstone didn't come up with a design that omits more of the internal cables. The Enermax liberty for example only uses a few internal cables to power the cable management PCB, and if Silverstone had taken a similar approach they could have made room for a larger secondary heatsink. We have seen this from other companies like OCZ as well.


The secondary capacitors are made by Taepo.



Test Setup

As usual we are testing with our Chroma programmable loads to fully load each rail to a specific amount. This is important to get truly accurate results and not merely approximate values. The tests are conducted in two different temperature environments. One is normal room temperature of 25-26°C, while the second environment goes from room temperature and increases steadily up to 50°C. Especially during the higher temperatures we will see how good the power supplies are and what they're really made of. Components inside will perform much worse at higher temperatures, but we expect any good quality PSU to deal with such test conditions without failing.

Note: If you would like to know more about our testing methodology, equipment, and environment, please read our PSU testing overview.

DC Output Rails
PSU Load	3.3V Amps	3.3V Wattage	5V Amps	5V Wattage	5Vsb Amps	5Vsb Wattage	12V Amps	12V Wattage	Wattage All Rails
10%	1.45	4.86	1.82	9.16	0.23	1.16	4.16	50.50	66
20%	2.91	9.69	3.63	18.11	0.46	2.31	8.33	100.79	131
30%	4.36	14.34	5.45	26.98	0.69	3.44	12.49	150.51	195
40%	5.81	16.06	7.27	35.62	0.93	4.60	16.65	199.80	256
50%	7.27	23.70	9.08	44.04	1.16	5.71	20.82	248.80	322
60%	8.72	28.17	10.90	52.43	1.39	6.80	24.98	297.51	385
70%	10.17	32.54	12.72	60.67	1.62	7.86	29.15	348.63	450
80%	11.63	36.98	14.53	68.58	1.85	8.94	33.31	394.39	509
90%	13.08	41.20	16.35	76.36	2.08	9.94	37.47	440.95	568
100%	14.53	45.33	18.17	83.76	2.31	10.95	41.64	487.60	628

3.3V DC Output


The 3.3V rail is a bit better at the Decathlon than the Olympia. It drops with increasing load but that doesn't fall under the minimum specified voltage. The decreasing voltage doesn't have much to do with temperatures since the voltage drops are all nearly identical regardless of ambient temperature or input voltage. During transient load testing we have also seen good results. The Decathlon works quite well with changing loads and input voltages. It also showed no problems with a cold start that jumped from 0% to 100% load.

5.0V DC Output


The 5V rail has an outcome similar to that of the Olympia OP650. It's a little bit better but the voltage still drops under the specified limitation of 4.75V when using a 230VAC input at higher ambient temperatures.

5Vsb Output


From the stability point of view it is not a surprise to see a decrease in the 5Vsb rail, but it is still within specifications and shouldn't be a problem.

12V DC Output


The 12V rail is very stable and doesn't even come close to the lower limits. Given that the 12V output is arguably the most important, we are pleased to see that it also provides the best results. Still, Silverstone could work on minimizing voltage drops for all of the output rails.



Efficiency and PFC


The efficiency is as good as the Olympia and reaches up to 83% with 230VAC. With lower input voltages we still reach up to an 81% efficiency which is a very good result. The 230VAC efficiency is nearly the same regardless of the ambient temperatures, which indicates that the overall design and the components are of good quality and are not substantially affected by heat.



The Decathlon uses 1.19W with 115VAC and 1.7W with 230VAC which is not a great result. Consuming this much power to do essentially nothing is wasteful, and it would be better for users to click the little switch on the back if the system is not in use. The standby efficiency is fairly average but does better at higher levels.


With lower input voltages the power factor correction looks very good. The 230VAC result is worse, but that is to be expected. The overall PFC results are better than many of the other power supplies, however.



Temperatures, Fan Speed, and Acoustics




The secondary heatsink gets quite hot, which as mentioned is a result of the small volume/surface area. The bigger heatsink on the primary side performs much better. It's interesting to note that the exhaust temperatures are actually hotter than the primary heatsink in our room temperature testing.


The power supply does a good job at adjusting fans speed in response to increasing temperatures. With a 40-50°C ambient temperature the fan starts spinning faster much earlier. At normal room temperature the fan maxes out at 1900 RPM. Higher ambient temperature means faster rotational speeds, and with an ambient temperature of 50°C the fans reaches 2400 RPM in an attempt to get the PSU as much air as possible to help cool things down.


With a normal load this power supply should not be very audible in a PC system. It's not necessarily silent, but at room temperatures and moderate loads the fan only produces around 25dB(A) which is typically less than the noise other components produce. When it comes to loads of 400W and more, the power supply definitely isn't quiet anymore but that's to be expected. In a 25°C environment, maximum load results in a noise level of 36dB(A). If you happen to run in a hotter climate/environment, noise levels can reach as high as 44dB(A). However, that result is still pretty good in comparison to other competing power supplies.



Conclusion

Despite the voltage drop on the 5V rail (especially under 230VAC input) this power supply still leaves us with a favorable impression. The internal design and the arrangement of components are very good, and Silverstone uses high-quality components rated for higher temperatures. The end result is very good performance, even in harsher environments. Noise levels are also better than most competing power supplies.

The two biggest flaws with the Decathlon DA650 are the same as those of the Olympia OP650. The secondary heatsink is too small and has difficulty dissipating heat at higher loads. It would be great to see a bigger heatsink in the next version, revision, or series from Silverstone. The second problem is the big voltage drop that occurs on most of the rails, and although most of the rails remain within specifications there is still clearly room for improvement. The 12V rail doesn't have as significant of a voltage drop, and we would like to see the same attention given to the other rails. We are staying in contact with Silverstone, and if we receive any new information on this issue we will be sure to update the article.


The efficiency and standby efficiency are above average as we have seen with the Olympia. Reaching a maximum of 83% efficiency, the result is very good, particularly with 230VAC. With an input of 100VAC we still reach 80% efficiency. The standby efficiency is better than what we have seen with other units, although the unit uses a little too much power when the system is turned off.

The Decathlon DA650 is available all over Europe for about 160 EUR. Availability in the states isn't as good, but Newegg is carrying the DA650 with a current price of $160 and a $20 mail-in rebate. It's also noteworthy that we couldn't find any particular differences between the soldered cables of the OP650 and the modular cables used in the DA650. We basically have two power supplies that are almost exactly the same, and the user can decide whether or not they want detachable cables. The price is reasonable considering the quality, and both Silverstone 650W power supplies carry the same price (at least after rebate).