We would like to thank PNL-tec GmbH
for supplying the review sample.
RASURBO is a brand of PNL-tec GmbH, which is a German company founded in 2005 distributing cases, power supplies and cooling products. RASURBO products currently span into three categories: cases, power supply units (PSUs) and fans. As they state the main feature of their products is the unbeatable price/performance ratio, a very proud claim indeed that we will keep in mind while conducting this review.
RASURBO currently has three PSU series: REAL&Power, GaminX & Power and ECO&Power. The first of the aforementioned series includes four PSUs with capacities ranging from 350W to 650W. The test subject of today's review is RASURBO REAL&Power 550W (RAPM550 here after) PSU. This unit is 80 PLUS certified, EuP/ErP ready, features a semi-modular cabling system and is backed by two years of warranty. The unit's strongest point is definitely its price, 60€. If it manages to exhibit decent performance then, with this price, it will be a good solution for a small home/office PC.
|RASURBO RAPM550 Features & Specs
|Max. DC Output
||10°C - 50°C
||Over Voltage Protection
Under Voltage Protection
Over Current Protection
Over Power Protection
Short Circuit Protection
||135 mm Sleeve Bearing Fan (DFS132512H)
||150 mm (W) x 86 mm (H) x 160 mm (D)
||ATX12V v2.3, EPS 2.91
|Price at time of review
All protections, besides Over Temperature are present. Price is on the low side but unfortunately the same goes for warranty which is only two years.
| RASURBO RAPM550 Power Specs
|Total Max. Power
There are two +12V rails with non-matchd power distribution. The combined maximum power of +12V is only 70W below the unit's max rated capacity. Strangely the 5V rail is rated much lower than the 3.3V one, at only 15A max.
Cables & Connectors, Power Distribution
|ATX connector (510 mm)
|4+4 pin EPS12V/ATX12V (580 mm)
|6+2 pin PCIe (500 mm)
|4 pin Molex (500 mm+150 mm+150 mm) / FDD (+150 mm)
||3 / 1
|SATA (500 mm+150 mm+150 mm)
|SATA (500 mm+150 mm)
The number of peripheral connectors is limited. Also we would like to see one or, even better, two more SATA connectors. We are a bit surprised that RASURBO did not include an additional SATA or peripheral cable in the bundle since one connector is left unused on the modular panel when all provided SATA/peripheral cables are connected. Cable length in general terms is sufficient and the distance between connectors is the recommended by ATX spec. Finally all wires have 18 AWG size.
Power distribution is not good since the EPS connector feeds from the same +12V rail with the two PCIe connectors, which normally should be on a different rail. On top of that 12V2 is weaker than 12V1 by 8A! This is really weird. Either the power specifications on the manual/label of the PSU are wrong or the manufacturer did not choose the optimum power configuration for this model.
The face of the box features a vivid color scheme. On the front there are also some badges which inform us that the PSU is 80 PLUS certified, EuP/ErP ready, has Active PFC and uses a semi modular cabling scheme. If you want more information don't search on the back side of the packaging, because this is plain black with nothing on it. Take a look instead on the top and its side edges.
In the packaging the PSU is protected by cardboard and white cloth. We would prefer, of course, packing foam or at least some bubble wrap. The bundle includes two Velcro cable ties, three zip ties, an AC power cord, a set of fixing bolts, the modular cables and a user's manual.
The finish is green and black. The green areas are glossy while the black ones are semi-matte. A fairly large grommet covers the cables' exit hole and protects the nylon sleeved cables. Strangely enough the fan does not have a badge on its center. In general external quality is exactly what you should expect from a low priced PSU, nothing extraordinary, but not bad either.
A Look Inside
Before reading this page we strongly suggest to take a look at this
article, which will help you understand the internal components of a PSU much better.
With the primary&secondary heatsinks removed the view is much clearer, don't you think? The OEM of the unit is HEC-COMPUCASE
The first part of the transient filtering stage as usual starts at the AC receptacle. One X and two Y caps are located there. It continues on the main PCB with two coils, two Y&X caps and an MOV. The bridge rectifier, a KBU 10J
, is bolted to a heatsink.
In the APFC stage two mosfets, FDP18N50
, and the necessary boost diode are used. The smoothing/reservoir capacitor is provided by CapXon (330μF, 400V, 85°C). As primary switches we find two Infineon 20N60C3
mosfets. The combo PFC/PWM controller resides on a vertical daughter-board and once more is a Champion CM6800.
In the secondary, passive design is used for the regulation of all rails. The +12V rail is handled by two SBR30A50CT
while 5V and 3.3V are generated by two STPS30L45CT
. The presence of only two toroidal chokes indicates that group regulation is used so the bigger coil is shared by 12V/5V and the smaller one is for the rectification and filtering of 3.3V. All capacitors in the secondary are provided by Teapo and are labeled at 105°C. In the secondary side there is also the protections IC, a Weltrend WT7525
, which is soldered on a daughter-board. It supports up to two +12V rails matching this way the number of PSU's +12V rails. The odd thing here is that this IC does not support OVP (Over Voltage Protection) although the manufacturer states that it is present in RAPM550.
Soldering and workmanship on the main and modular PCBs are good enough for the price range of the unit.
The cooling fan is provided by Young Lin Tech, its model number is DFS132512H
(12V, 0.25A, 1700RPM, 91.16 CFM, 36.28 dBA) and it uses sleeve bearing.
All measurements are performed utilizing a custom designed and built load tester, called Faganas, which is able to stress PSUs up to 1800 Watts. We also use a DS1M12 (Stingray) oscilloscope, a CHY 502 thermometer, a Fluke 175 multimeter and an Instek GPM-8212 power meter. Furthermore, in our setup we have included a wooden box, which along with a heating element is used as a Hot Box. Finally, we have at our disposal nine electronic loads (six Array 3711A, 300W each, and three Array 3710A, 150W each), a Rigol 1052E oscilloscope and a CEM DT-8852 sound level meter. In the near future the electronic loads will form our new test set up, which with the help of our custom built software will have the same capabilities with the, ultra expensive, Chroma ATEs. In this
article you will find more details about our equipment and the review methodology we follow.
Voltage Regulation Charts
The following charts show the voltage values of the main rails, recorded over a range from 60W to the maximum specified load, and the deviation (in percent), when compared with the voltage values at 60W load.
In this chart you will find the efficiency of RAPM550 at low loads and at loads equal to 20-100% of PSU’s maximum rated load.
Voltage Regulation and Efficiency Measurements
The first set of tests reveals the stability of voltage rails and the efficiency of RAPM550. The applied load equals to (approximately) 20%, 40%, 50%, 60%, 80% and 100%, of the maximum load that the PSU can handle. In addition, we conduct two more tests. In the first we stress the two minor rails (5V & 3.3V) with the maximum load that our tester can apply to these rails, while the load at +12V is only 2A and in the second test we dial the maximum load that +12V can handle while load at minor rails is minimum.
| Voltage Regulation & Efficiency Testing Data
Let's start with the positives first: the PSU manages to deliver its full power even at 50°C ambient and efficiency peaks at 40% load with an impressive 85.99% reading, a very high number for a plain 80 PLUS unit. We can pretty much say that all goes well until we dialed 100% load. Then suddenly the +12V rail registers a huge voltage drop, showing clearly that it cannot handle the extra load well and 3.3V rail goes out of ATX spec. On top of that efficiency drops by a huge 2.4% percentage. As it seems RAPM550 going from 450W to 550W is stressed pretty hard, so it would be better if it was labeled as a 450W PSU. Then voltage regulation on all rails along with efficiency would be much better. Finally, the CL1 test showed weaknesses of the group regulation design and the fail in CL2 test proves that +12V cannot handle the load that the manufacturer claims, since we pulled around 470W from +12V at this test and power specs say that the same rail can deliver up to 480W, a very optimistic number according to our readings.
Efficiency at Low Loads
In the next tests, we measure the efficiency of RAPM550 at loads much lower than 20% of its maximum rated load (the lowest load that the 80 Plus Standard measures). The loads that we dial are (approximately) 40, 65 and 90W. This is important for scenarios in which a typical office PC is in idle with power saving turned on.
| Efficiency at Low Loads
If we take into account the efficiency certification of this PSU then at low loads it performed pretty well since with 63.57W load, efficiency almost reached 80% and with 88.47W load it registered an impressive 83%.
Power Consumption in Idle & Standby
In the table below you will find the power consumption and the voltage values of all rails (except -12V), when the PSU is in idle mode (On but without any load at its rails) and the power consumption when the PSU is in standby (without any load at 5VSB).
| Idle / Standby
Our power meter measured very low phantom power so RAPM550 is definitely ErP Lot 6 ready (<1W at standby mode).
Advanced Transient Response Tests
In these tests we monitor the response of the PSU in two different scenarios. First a transient load (10A at +12V, 5A at 5V and 6A at 3.3V) is applied for 50 ms to the PSU, while the latter is working at a 20% load state. In the second scenario the PSU, while working with 50% load, is hit by the same transient load (with the exception now that load at 3.3V is increased by 4A). In both tests, we measure the voltage drops that the transient load causes, using a Labjack that is attached to our loader and the Stingray oscilloscope. In any case voltages should remain within the regulation limits specified by the ATX specification. We must stress here, that the above tests are crucial, since they simulate transient loads that a PSU is very likely to handle (e.g. starting of a RAID array, an instant 100% load of CPU/VGAs etc.) We call these tests “Advanced Transient Response Tests” and they are designed to be very tough to master, especially for PSUs with capacities lower than 500W.
| Advanced Transient Response 20%
| Advanced Transient Response 50%
The PSU's small capacity was an aggravating factor in these tests. The +12V rail managed to control the applied transient loads and staid well within regulation limits but the minor rails and especially 3.3V suffered, a lot, in these tests. The final verdict here is not good for RAPM550, at least for the minor rails.
Below you will find the oscilloscope screenshots that we took during Advanced Transient Response Testing.
Transient Response at 20% Load
Transient Response at 50% Load
Turn-On Transient Tests
In the next set of tests we measure the response of the PSU in simpler scenarios of transient loads, during the turn on phase of the PSU. In the first test we turn off the PSU, dial 2A load at 5VSB and then switch on the PSU. In the second test, while the PSU is in standby, we dial the maximum load that +12V can handle and we start the PSU. In the last test, while the PSU is completely switched off (we cut off power or switch off the PSU's On/Off switch), we dial the maximum load that +12V can handle and then we switch on the PSU from the loader and we restore power. The ATX specification states that recorded spikes on all rails should not exceed 10% of their nominal values (e.g. +10% for 12V is 13.2V and for 5V is 5.5V).
RAPM550 passed these tests with flying colors since it did not register any voltage overshoots and rise time was constantly within ATX spec limits.
In the following table you will find the ripple levels that we measured on the main rails of RAPM550. According to ATX specification the limits are 120 mV (+12V) and 50 mV (5V & 3.3V).
Ripple on the +12V rail is well within ATX spec limits but in a contemporary PSU we don't like to see close to 90mV readings. The minor rails here performed much better and only at CL2 test 3.3V registered over 30mV ripple. Similar to the voltage regulation tests if you notice the big difference in ripple readings of +12V between 80% load and 100% you will see that the PSU is over-stressed to deliver those 100 extra Watts.
Ripple at Full Load
In the following oscilloscope screenshots you can see the AC ripple and noise that the main rails registered (+12V, 5V, 3.3V). The bigger the fluctuations on the oscilloscope's screen the bigger the ripple/noise. For RAPM550 we have set 0.02 V/Div (each vertical division/box equals to 0.02V) as standard for all below screenshots.
Ripple at Crossload 1
The order of images is +12V, 5V and 3.3V.
Ripple at Crossload 2
As above the order of images is +12V, 5V and 3.3V.
Value and Conclusion
- Currently the RASURBO RAPM550 is not sold in the U.S. In Europe it can be found for 60€.
- Managed full power at 50°C ambient (but 3.3V went out of voltage regulation limits)
- Good efficiency levels for a plain 80 PLUS certified unit
- Reasonable price
- Semi-modular cabling system
- Loose voltage regulation at +12V and 3.3V
- Bad performance at Crossload tests
- 5V and 3.3V rails failed in Advanced Transient Response tests
- High ripple at +12V
- Two year warranty
- Only three peripheral connectors
- Power distribution is not optimal
||The RASURBO REAL&Power series targets the budget oriented users that need an affordable PSU to power a low/middle end system. At least in Europe it's not easy to find a semi-modular PSU at 60 Euros, so RAPM550 earns a point here. Also the fact that it managed to operate at full power even at 50°C pleased me. However the loose voltage regulation at +12V and the sudden drop in performance over 440 W troubled me. In Crossload test 2 the +12V rail clearly showed that it can not handle the power that the manufacturer claims. On top of that Advanced Transient Response tests proved to be a Waterloo for RAPM550 since its minor rails performed bad. Thankfully the most significant rail, +12V, handled the transient loads well. In ripple/suppression measurements the situation reverses and +12V exhibits mediocre performance, here the minor rails have better DC quality.|
In my humble opinion RAPM550 should be characterized as a 450W unit, not because it can't deliver 550W of power, but because it performs quite well up to this mark. If your needs are covered with about 450W and you are on a tight budget then RAPM550 is a decent choice but if you expect to regularly draw well beyond 450 W of power, then you should look elsewhere.