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[nextpage title=”Introduction”]
Rosewill is a very popular brand in the United States and their RD600N-2SB-SL-BK power supply is a rebadged Solytech SL-8600EPS, featuring active PFC, 120 mm fan and two auxiliary power plugs for video cards under SLI or CrossFire configuration. Is this a good product? Can it really deliver 600 W? Let’s see.
This power supply from Solytech is found in three different versions:
- With a 120 mm fan like this reviewed model from Rosewill and Apex SL-8600EPS;
- With two 80 mm fans like Rosewill RD600N-2DB-SL, Rosewill RD600N-2DC-SL, MSI TurboStream 600 W and Satellite SL-8600EPS;
- With a modular cabling system, like Satellite SL-8600EPS-Modular and Antler EPS600W.
Besides the external aspect, internally all these power supplies are exactly the same product. So even though this is a review for Rosewill RD600N-2SB-BK power supply the results should be valid for all the power supplies listed above.
Solytech is also known by several other names, like Deer, L&C, Apex, Allied, SuperCase, Antler, Austin and others, and they seem to be around since the beginning of times with a not so good reputation (read this review and these comments to learn more about this company). Also it seems that Foxconn has ownership interest on this company. Of course we will check by ourselves whether this power supply is a good product or not.
By the way, we are still intrigued why MSI chose Solytech as the vendor for their power supplies. Usually big manufacturers prefer to choose an exclusive model for their line of power supplies, but power supplies from Solytech are far from exclusive and can be found on the market under several different brands, as you can see from above.
Figure 1: Rosewill RD600N-2SB-SL-BK power supply.
Figure 2: Rosewill RD600N-2SB-SL-BK power supply.
This power supply comes with a 20/24-pin motherboard cable, an ATX12V connector and an EPS12V connector (installed on the same cable) and five peripheral cables: one auxiliary power cable for video cards with two 6-pin connectors, two cables with two standard peripheral power connectors and one floppy disk drive power connector each and two cables with two SATA power plugs each.
In our opinion the number of connectors isn’t enough for the target audience of this power supply, with only four peripheral power plugs and four SATA power plugs. This power supply should have at least six SATA power plugs.
Also the two video card auxiliary power connectors are installed on the same cable and we prefer power supplies that use individual cables for a better power/current distribution.
All wires from this power supply are 18 AWG, which is perfect for a 600 W power supply.
On the aesthetic side all wires are protected with a nylon sleeving, but this protection doesn’t come from inside the power supply housing.
Now let’s take an in-depth look inside this power supply.
[nextpage title=”A Look Inside The RD600N-2SB-SL-BK”]
We decided to disassemble this power supply to see what it looks like inside, how it is designed, and what components are used. Please read our Anatomy of Switching Power Supplies tutorial to understand how a power supply works and to compare this power supply to others.
This page will be an overview, and then in the following pages we will discuss in detail the quality and ratings of the components used.
The first thing that caught our eye when we disassembled this power supply was the fact this power supplies uses a transformer instead of a coil on its active PFC circuit (see the transformer with the “APFC” marking on top).
Figure 3: Overall look.
Figure 4: Overall look.
Figure 5: Overall look.
[nextpage title=”Transient Filtering Stage”]
As we have mentioned in other articles and reviews, the first place we look when opening a power supply for a hint about its quality, is its filtering stage. The recommended components for this stage are two ferrite coils, two ceramic capacitors (Y capacitors, usually blue), one metalized polyester capacitor (X capacitor), and one MOV (Metal-Oxide Varistor). Very low-end power supplies use fewer components, usually removing the MOV and the first coil.
This power supply brings all the recommended components plus one extra X capacitor (and another extra X capacitor after the rectifying bridge). The MOV is located after the rectification bridge, and not before as usual. And the fuse is located on the first part of the transient filtering stage, i.e., on a small printed circuit board attached to the main AC power plug. This power supply uses a fuse holder, a thing that is rare to see nowadays (most power supplies nowadays come with their fuses soldered directly on the printed circuit board).
Figure 6: Transient filtering stage (part 1).
Figure 7: Transient filtering stage (part 2).
< p>In the next page we will have a more detailed discussion about the components used in the Rosewill RD600N-2SB-SL-BK.
[nextpage title=”Primary Analysis”]
On this page we will take an in-depth look at the primary stage of Rosewill RD600N-2SB-SL-BK. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.
This power supply uses one GBU1006 rectifying bridge in its primary, capable of delivering up to 10 A at 100° C, if it has a heatsink attached, which is the case (without the heatsink the current limit drops to 3.2 A). This is an adequate rating for a 600 W power supply. The reason why is that at 115 V this unit would be able to pull up to 1,150 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 920 W without burning this component. Of course we are only talking about this component and the real limit will depend on all other components from the power supply.
On this power supply the rectifying bridge is protected by a rubber tape, as you can see in Figure 8.
Figure 8: Rectifying bridge.
Figure 9: Rectifying bridge.
The active PFC circuit uses two FQA24N50 power MOSFET transistors, each one capable of delivering up to 15.2 A at 100° C (or 24 A at 25° C, see the difference temperature makes). They are located on the same heatsink as the switching transistors.
The switching section from this power supply uses two SPW20N60C3 power MOSFET transistors in the traditional two-transistor forward configuration. Each switching transistor can handle up to 13.1 A at 100° C (or 20.7 A at 25° C, once again see the difference temperature makes).
Figure 10: Switching transistor, active PFC transistor and the other switching transistor (the second active PFC transistor is on the other side of the heatsink).
The primary is controlled by a CM6800 integrated circuit, which is a very popular PFC/PWM combo controller.
Figure 11: PFC/PWM controller.
We couldn’t recognize the manufacturer of the electrolytic capacitor used on the active PFC circuit. It is rated at 85° C.
[nextpage title=”Secondary Analysis”]
This power supply uses six Schottky rectifiers on its secondary.
The +12 V output is produced by two MBR40100PT Schottky rectifiers connected in parallel, which can deliver up to 40 A each (20 A per internal diode each, measured at 162° C). The maximum theoretical current the +12 V line can deliver is given by the formula I / (1 – D), where D is the duty cycle used and I is the maximum current supported by the rectifying diode (which in this case is made by two 20 A diodes in parallel). Just as an exercise, we can assume a typical duty cycle of 30%. This would give us a maximum theoretical current of 57 A or 684 W for the +12 V output. The maximum current this line can really deliver will depend on other components, in particular the coil used.
The +5 V output is produced by two MBR4045PT Schottky rectifiers connected in parallel, which support up to 40 A (20 A per internal diode each, measured at 125° C) each. The maximum theoretical current the +5 V line can deliver is given by the formula I / (1 – D), where D is the duty cycle used and I is the maximum current supported by the rectifying diode (which in this case is made by two 20 A diodes in parallel). Just as an exercise, we can assume a typical duty cycle of 30%. This would give us a maximum theoretical current of 57 A or 285 W for the +5 V output. The maximum current this line can really deliver will depend on other components, in particular the coil used.
The +3.3 V output is produced by two other MBR4045PT Schottky rectifiers connected in parallel. The maximum theoretical current the +3.3 V line can deliver is given by the formula I / (1 – D), where D is the duty cycle used and I is the maximum current supported by the rectifying diode (which in this case is made by two 20 A diodes in parallel). Just as an exercise, we can assume a typical duty cycle of 30%. This would give us a maximum theoretical current of 57 A or 188 W for the +3.3 V output. The maximum current this line can really deliver will depend on other components, in particular the coil used.
As you can see this stage is clearly overspec’ed, which is terrific.
Figure 12: Three of the six Schottky rectifiers used on the secondary.
The thermal sensor from this power supply is located on the secondary heatsink, as you can see in Figure 12. This sensor is used to control the fan speed according to the power supply internal temperature and also to shut the power supply down if it implements over temperature protection (OTP).
This power supply uses a PS223 monitoring integrated circuit, which is in charge of the power supply protections, like OCP (over current protection). This IC also provides over voltage protection (OVP), under voltage protection (UVP) and over temperature protection (OTP), but not over power protection (OPP).
Figure 13: Monitoring integrated circuit.
We couldn’t identify the manufacturer from the electrolytic capacitors used on the secondary, which are rated at 105° C.[nextpage title=”Power Distribution”]
In Figure 14, you can see the power supply label containing all the power specs.
Figure 14: Power supply label.
As you can see this power supply has two virtual +12 V rails. As mentioned before we could clearly see on the printed circuit board that each rail was really connected to the over current protection (OCP) circuit, but this protection failed during our tests (more about this later) meaning that in practical terms this power supply is working as a single-rail unit.
These two rails are divided as following:
- +12V1: Main motherboard cable, auxiliary power cable for video cards and all peripheral cables.
- +12V2: EPS12V/ATX12V cable.
Now let’s see if this power supply can really deliver 600 W of power.
[nextpage title=”Load Tests”]
We conducted several tests with this power supply, as described in the article Hardware Secrets Power Supply Test Methodology.
We tested this power supply under five different load patterns, trying to pull around 20%, 40%, 60%, 80%, and 100% of its maximum capacity (actual percentage used listed under “% Max Load”), watching how the reviewed unit behaved under each load.
If you add all the power listed for each test, you may find a different value than what is posted under “Total” below. Since each output can vary slightly (e.g., the +5 V output working at +5.10 V), the actual total amount of power being delivered is slightly different than the calculated value. On the “Total” row we are using the real amount of power being delivered, as measured by our load tester.
+12V2 is the second +12V input from our load tester and during our tests it was connected to the power supply EPS12V connector, which is the only thing connected to the unit’s +12V2 rail. So this time +12V1 and +12V2 inputs from our load tester where really connected to the +12V1 and +12V2 rails from the reviewed power supply.
| Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
| +12V1 | 4 A (48 W) | 9 A (108 W) | 13 A (156 W) | 17.5 A (210 W) | 20 A (240 W) |
| +12V2 | 4 A (48 W) | 9 A (108 W) | 13 A (156 W) | 17.5 A (210 W) | 20 A (240 W) |
| +5V | 1 A (5 W) | 2 A (10 W) | 4 A (20 W) | 6 A (30 W) | 12 A (60 W) |
| +3.3 V | 1 A (3.3 W) | 2 A (6.6 W) | 4 A (13.2 W) | 6 A (19.8 W) | 12 A (39.6 W) |
| +5VSB | 1 A (5 W) | 1 A (5 W) | 1.5 A (7.5 W) | 2 A (10 W) | 2.5 A (12.5 W) |
| -12 V | 0.5 A (6 W) | 0.5 A (6 W) | 0.5 A (6 W) | 0.5 A (6 W) | 0.5 A (6 W) |
| Total | 115.5 W | 242.5 W | 356.3 W | 480.4 W | 593.8 W |
| % Max Load | 19.3% | 40.4% | 59.4% | 80.1% | 99.0% |
| Room Temp. | 47.3° C | 47.3° C | 47.4° C | 48.1° C | 47.3° C |
| PSU Temp. | 53.4° C | 52.9° C | 53.2° C | 54.9° C | 56.1° C |
| Load Test | Pass | Pass | Pass | Pass | Pass |
| Voltage Stability | Pass | Pass | Pass | Pass | Pass |
| Ripple and Noise | Pass | Pass | Pass | Pass | Pass |
| AC Power | 141 W | 287 W | 428 W | 586 W | 752 W |
| Efficiency | 81.9% | 84.5% | 83.2% | 82.0% | 79.0% |
| Final Result | Pass | Pass | Pass | Pass | Pass |
This power supply can really deliver 600 W of power at a room temperature of over 45° C, which is great.
The problem when we tried to pull 600 W from this unit was that when the power supply was hot, it wouldn’t turn on with a load around 600 W, a typical behavior of a protection kicking in. We know it wasn’t the over temperature protection (OTP) because the power supply would turn on with any other load pattern below 100% when it was hot. It looked like over power protection (OPP) but the monitoring integrated circuit used (PS223) doesn’t support this protection, even though Solytech lists OPP as a feature present on this power supply. What was stranger was that this protection was active only when we turned on the power supply with our 100% load already selected, if we turned on our power supply with a different load and then selected our 100% load the power supply would work just fine.
As you can see efficiency was above 80% on all tests but when pulled 600 W from this unit, when efficiency dropped to 79%. Efficiency when we pulled around 40% of the power supply maximum labeled capacity (240 W) was very nice at 84.5%.
Voltage stability, on the other hand, was the highlight of this product, with all outputs between 3% of their nominal voltage in almost all tests, which is excellent (ATX standard allows voltages to be up to 5% from their nominal values – 10% in the case of the -12 V output).
Noise level on +12 V outputs was higher than the noise level found on good power supplies, but still inside ATX specs. Noise level at +5 V and at +3.3 V was low. Below you can see noise level for the test number five.
Figure 15: Noise level at +12V1 with power supply delivering 600 W (78.2 mV).
Figure 16: Noise level at +12V2 with power supply delivering 600 W (84 mV).
Figure 17: Noise level at +5 V with power supply delivering 600 W (20.6 mV).
Figure 18: Noise level at +3.3 V with power supply delivering 600 W (15 mV).
Now let’s see if we could pull even more power from this unit and our tests of the power supply protections.
[nextpage title=”Overload Tests”]
Before performing our overload tests we always like to test first if the over current protection (OCP) circuit is really active and at what level it is configured.
We configured +12V2 input from our load tester with a low current (1 A) and increased current on +12V1 input (which was connected to the power supply +12V1 rail) until the power shut down. This happened only when we tried to pull more than 32 A, a value that is too far from the labeled 22 A limit that each +12 V rail has in theory. Investigating further this question we discovered that the
power supply was shutting down not because of OCP, but because of over voltage protection (OVP). When we tried pulling 32.7 A from the +12V1 rail, ripple was at 840 mV, making voltages to be completely out of range and thus activating this other protection.
So at least with us over current protection was either disabled or configured at a value that was too high, making this power supply to operate as a single rail power supply (the difference between single rail and multi rail power supplies is the addition of multiple over current protection circuits on the later).
When we configured our load tester to pull more than 600 W we had the issue described in the previous page – the power supply wouldn’t turn on, only if we first selected a lighter load first and then move to the heavier load.
The maximum amount of power we could pull from Rosewill RD600N-2SB-SL-BK with it still working inside ATX specs can be found below. At this configuration noise level was very high, around 100 mV at +12V1 and +12V2, with noise level at -12 V touching 120 mV.
| Input | Maximum |
| +12V1 | 22 A (264 W) |
| +12V2 | 22 A (264 W) |
| +5V | 16 A (80 W) |
| +3.3 V | 16 A (52.8 W) |
| +5VSB | 2.5 A (12.5 W) |
| -12 V | 0.5 A (6 W) |
| Total | 675 W |
| % Max Load | 112.5% |
| Room Temp. | 42.6° C |
| PSU Temp. | 46.5° C |
| Load Test | Pass |
| Voltage Stability | Pass |
| Ripple and Noise | Pass |
| AC Power | 864 W |
| Efficiency | 78.1% |
| Final Result | Pass |
Short circuit protection (SCP) worked fine for both +5 V and +12 V lines.
[nextpage title=”Main Specifications”]
Rosewill RD600N-2SB-SL-BK power supply specs include:
- ATX12V 2.2
- EPS12V 2.91
- Nominal labeled power: 600 W.
- Measured maximum power: 675 W at 42.6° C.
- Labeled efficiency: At least 80%.
- Measured efficiency: Between 79.0% and 84.5% at 115 V.
- Active PFC: Yes.
- Motherboard Power Connectors: One20/24-pin connector, one ATX12V connector and one EPS12V connector.
- Video Card Power Connectors: Two 6-pin connectors.
- Peripheral Power Connectors: Four.
- Floppy Disk Drive Power Connectors: Two.
- SATA Power Connectors: Four.
- Protections: over voltage (OVP, tested and working), over power protection (OPP, tested and apparently working, see text for details) and short-circuit (SCP, tested and working).
- Warranty: Three years.
- Real model: Solytech SL-8600EPS
- More Information: https://www.rosewill.com
- Average price in the US*: USD 68.00.
* Researched at Newegg.com on the day we published this review.[nextpage title=”Conclusions”]
We were surprised with this power supply. With so many people saying bad things about the many previous incarnations of Solytech we were expecting a power supply with low efficiency and that couldn’t deliver its labeled power.
This unit could deliver its labeled 600 W at 47.3° C, which is wonderful, plus we could pull up to 675 W from it, and it survived!
But this isn’t a “perfect” power supply. Efficiency drops below 80% when pulling its full 600 W power and also noise level is far higher than we wanted to see.
OCZ StealthXStream 600 W is a better product because it provides a higher efficiency and lower noise level than Rosewill RD600N-2SB-SL-BK. However, if you want an honest 600 W power supply that costs less than this model from OCZ, Rosewill RD600N-2SB-SL-BK is certainly a very good option if you are on budget. Just be careful, Rosewill’s website says that this unit’s MRSP is of USD 126, which is insane. Newegg.com sells this unit at its correct USD 68 price tag.
Keep also in mind that there are several other power supplies that are internally identical to Rosewill RD600N-2SB-SL-BK (see a complete list on the first page) and they should get the same performance as the reviewed model.
Researching on the web we found out that MSI TurboStream 600 W is being sold by only USD 56 at Amazon.com, bringing an even better cost/benefit ratio than this model from Rosewill (even though internally these two units are identical, this model from MSI uses two 80 mm fans instead of one 120 mm fan though).
In summary, comments saying bad things about this power supply on forums around the web are pure speculation, based solely on Solytech’s past and not on actual testings. Of course there are better 600 W units around, if you have the money to buy them. If you don’t, this unit is a very good choice if you have only up to USD 70 to spend on a power supply.