[nextpage title=”Introduction”]
We also like to review low-end products from time to time so people with a serious budget restriction can have an idea whether it is worthwhile to buy cheap products or not. Today we are going to take an in-depth look at the Elite Power 350 W (RS-350-PSAR-I3) from Cooler Master. Can it really deliver its rated power? Is it worthwhile giving it a shot if you don’t have a lot of money to spend on a power supply? Let’s see.
Cooler Master uses all sort of vendors for their power supplies. This particular model is manufactured by Solytech, but the 400 W and 460 W models from the same series are manufactured by FSP, therefore this particular model is a completely different animal. On their other low-end series, Extreme Power and Extreme Power Plus, Cooler master uses another two vendors, AcBel Polytech and Seventeam, depending on the model. And they also use other vendors for their other power supply series. Phew!
Figure 1: Cooler Master Elite Power 350 W power supply
Figure 2: Cooler Master Elite Power 350 W power supply
The Cooler Master Elite Power 350 W is 5 ½” (14 cm) deep, using a 120-mm sleeve bearing fan on its bottom (Globe Fan S1202512L). This unit does not feature a PFC circuit, as you can see by the presence of a 115 V/230 V switch in Figure 1, being based on the outdated half-bridge topology.
No modular cabling system is provided and cables don’t have a nylon protection. The cables included are:
- Main motherboard cable with a 20/24-pin connector, 16.9” (43 cm) long
- One cable with two ATX12V connectors that together form one EPS12V connector, 18.9” (48 cm) long
- One cable with three SATA power connectors, 13.4” (34 cm) to the first connector, 5.9” (15 cm) between connectors
- One cable with three standard peripheral power connectors and one floppy disk drive power connector, 13.8” (35 cm) to the first connector, 5.9” (15 cm) between connectors
On the good side, all cables use 18 AWG wires, which is the minimum recommended gauge. On the other hand, the cable configuration and reduced number of connectors and lack of a video card power connector clearly shows that we are dealing with a low-end product. Although this unit has three SATA power connectors, you may have trouble installing a SATA hard drive and a SATA optical drive, depending on the distance between them inside your case.
Figure 3: Cables
Let’s now take an in-depth look inside this power supply.
[nextpage title=”A Look Inside The Cooler Master Elite Power 350 W”]
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.
On this page we will have an overall look, and then in the following pages we will discuss in detail the quality and ratings of the components used. As already explained, this unit uses an internal design that is completely different from the one used on the 400 W and 460 W models.
Figure 4: Top view
Figure 5: Front quarter view
Figure 6: Rear quarter view
Figure 7: Printed circuit board
[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.
The transient filtering stage of the Cooler Master Elite Power 350 W is impeccable, coming with all required components plus one extra X capacitor and two extra Y capacitors. This is rare to see in a low-end power supply. Kudos to Cooler Master.
Figure 8: Transient filtering stage (part 1)
Figure 9: Transient filtering stage (part 2)
In the next page we will have a more detailed discussion about the components used in the Cooler Master Elite Power 350 W.
[nextpage title=”Primary Analysis”]
On this page we will take an in-depth look at the primary stage of the Cooler Master Elite Power 350 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.
This power supply uses one GBU606 rectifying bridge, which supports up to 6 A at 100° C if a heatsink is used, which is not the case. Without a heatsink, the maximum current drops to 2.8 A at 100° C. Therefore, this unit would be able to pull up to 322 W from a 115 V power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 258 W without burning itself out. Of course we are only talking about this component and the real limit will depend on all other components from the power supply.
Figure 10: Rectifying bridge
This unit is based on the obsolete half-bridge topology using two 2SD209L power NPN transistors on its switching section. Each transistor is capable of handling up to 12 A at 25° C. Unfortunately the manufacturer does not say the current limit at 100° C. These are the same transistors used on the 400 W and 460 W models, even though they are manufactured by a different company.
Figure 11: Switching transistors
The switching transistors are controlled by an ATX2005 PWM controller, which is located on the secondary from the power supply.
Figure 12: PWM controller
The two electrolytic capacitors from the voltage doubler are labeled at 85° C (we couldn’t recognize the brand).
Let’s now take a look at the secondary from this power supply.
[nextpage title=”Secondary Analysis”]
This power supply has three Schottky rectifiers on its secondary heatsink.
The maximum theoretical current each 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. Since this unit is based on the half-bridge topology, the duty cycle used is of 50%.
The +12 V output uses one SBL3060PT Schottky rectifier, which supports up to 30 A (15 A per internal diode), giving us a maximum theoretical current of 30 A or 360 W for the +12 V output.
The +5 V output uses one STPS3045CW Schottky rectifier, which supports up to 30 A (15 A per internal diode at 155° C, 0.84 V maximum voltage drop), giving us a maximum theoretical current of 30 A or 150 W for the +5 V output.
The +3.3 V output uses another STPS3045CW Schottky rectifier, giving us a maximum theoretical current of 30 A or 99 W for the +3.3 V output.
All these numbers are theoretical. The real amount of current/power each output can deliver is limited by other components, especially by the coils used on each output.
Figure 13: +3.3 V, +12 V and +5 V rectifiers
The outputs are monitored by the ATX2005 integrated circuit shown in Figure 12. This chip offers only over voltage protection and under voltage protection.
[nextpage title=”Power Distribution”]
On Figure 14 you can see this power supply label containing all its power specs.
Figure 14: Power supply label
As you can see, according to the label this unit has two +12 V rails, but this is a lie. All yellow (+12 V) wires are connected to the same spot on the printed circuit board, plus this unit doesn’t have over current protection, which is required for building multi-rail power supplies (click here to understand). Therefore, this unit has a single-rail design.
Let’s now see if this power supply can really deliver 350 W.
[nextpage title=”Load Tests”]
We conducted several tests with this power supply, as described in the article Hardware Secrets Power Supply Test Methodology.
First we tested this power supply with five different load patterns, trying to pull around 20%, 40%, 60%, 80%, and 100% of its labeled maximum capacity (actual percentage used listed under “% Max Load”), watching the behavior of the reviewed unit under each load. In the table below, we list the load patterns we used and the results for each load.
If you add all the powers listed for each test, you may find a different value than what is posted under “Total” below. Since each output can have a slight variation (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. In the “Total” row, we are using the real amount of power being delivered, as measured by our load tester.
The +12VA and +12VB inputs listed below are the two +12 V independent inputs from our load tester. During our tests, the +12VA and +12VB input were connected to the power supply single +12 V rail (the EPS12V connector was installed on the +12VB input of our load tester).
| Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
| +12VA | 2 A (24 W) | 4.5 A (54 W) | 7 A (84 W) | 9 A (108 W) | 11.25 A (135 W) |
| +12VB | 2 A (24 W) | 4.5 A (54 W) | 7 A (84 W) | 9 A (108 W) | 11 A (132 W) |
| +5V | 1 A (5 W) | 2 A (10 W) | 4 A (20 W) | 6 A (30 W) | 8 A (40 W) |
| +3.3 V | 1 A (3.3 W) | 2 A (6.6 W) | 4 A (13.2 W) | 6 A (19.8 W) | 8 A (26.4 W) |
| +5VSB | 1 A (5 W) | 1 A (5 W) | 1 A (5 W) | 1.5 A (7.5 W) | 2 A (10 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 | 67.5 W | 135.4 W | 213.1 W | 280.4 W | 348.4 W |
| % Max Load | 19.3% | 38.7% | 60.9% | 80.1% | 99.5% |
| Room Temp. | 42.4° C | 44.4° C | 45.4° C | 45.8° C | 46.8° C |
| PSU Temp. | 46.3° C | 46.1° C | 46.3° C | 46.8° C | 47.6° C |
| Voltage Regulation | Pass< /td> | Pass | Pass | Pass | Pass |
| Ripple and Noise | Pass | Pass | Pass | Pass | Pass |
| AC Power | 91.4 W | 176.3 W | 281.3 W | 372.6 W | 483.0 W |
| Efficiency | 73.9% | 76.8% | 75.8% | 75.3% | 72.1% |
| Final Result | Pass | Pass | Pass | Pass | Pass |
The Cooler Master Elite Power 350 W passed our tests, being able to deliver its labeled wattage at high temperatures.
Efficiency was lousy, between 72.1% and 76.8%, and because it can’t provide efficiency above 80% we can’t recommend this product.
On the other hand, voltage regulation was excellent, with all voltages within 3% of their nominal values (except the -12 V output, which was still inside the proper limits). The ATX12V specification allows voltages to be up to 5% from their nominal values (10% for the -12 V output). Therefore this power supply presents positive voltages closer to their nominal values than necessary all the time.
Noise and ripple levels were below the maximum allowed, with the +12 V output presenting low ripple and noise levels, but the +5 V and +3.3 V presenting relatively high levels, but still inside specs. Below you can see the results for the power supply outputs during test number five. The maximum allowed is 120 mV for the +12 V and -12 V outputs, and 50 mV for the +5 V, +3.3 V, and +5VSB outputs. All values are peak-to-peak figures.
Figure 15: +12VA input from load tester during test five at 348.4 W (33.4 mV)
Figure 16: +12VB input from load tester during test five at 348.4 W (34.2 mV)
Figure 17: +5V rail during test five at 348.4 W (36.6 mV)
Figure 18: +3.3 V rail during test five at 348.4 W (31.4 mV)
However, when we tried to pull more than 350 W from it, the unit burned (while we tried to pull 370 W).
[nextpage title=”Main Specifications”]
The main specifications for the Cooler Master Elite Power 350 W include:
- Standards: ATX12V 2.3
- Nominal labeled power: 350 W
- Measured maximum power: 348.4 W at 46.8° C
- Labeled efficiency: Above 70%
- Measured efficiency: Between 72.1% and 76.8% at 115 V (nominal, see complete results for actual voltage)
- Active PFC: No
- Modular Cabling System: No
- Motherboard Power Connectors: One 20/24-pin connector and two ATX12V connectors that together form an EPS12V connector
- Video Card Power Connectors: None
- SATA Power Connectors: Three on one cable
- Peripheral Power Connectors: Three on one cable
- Floppy Disk Drive Power Connectors: One
- Protections (as listed by the manufacturer): Over voltage (OVP), over current (OCP), over power (OPP) and short-circuit (SCP)
- Are the above protections really available? The manufacturer lists over current (OCP) and over power (OPP), protections that this unit doesn’t have, and misses to list under voltage protection (UVP), which is present
- Warranty: Two years
- Real Manufacturer: Solytech
- More Information: https://www.coolermaster.com/product.php?product_id=6617
- Average price in the US*: USD 25.00.
* Researched at Google Shopping on the day we published this review.
[nextpage title=”Conclusions”]
From all low-end power supplies sold by Cooler Master, the Elite Power 350 W is the most decent one, being able to deliver its labeled wattage at high temperatures, main voltages inside a tighter 3% regulation, noise and ripple inside the proper range, and coming with all required components in its transient filtering stage, including the MOVs. This happens because this unit is manufactured by a different vendor (Solytech) than the other three that Cooler Master uses for their other low-end power supplies.
The main problem with this unit is its lousy efficiency, always below 80% (between 72.1% and 76.8% during our tests). Therefore we can’t recommend it, although for its price it can be used in an “emergency situation” without putting your computer at risk.
The reviewed power supply burned when we tried to pull more than 350 W from it.
The manufacturer lists features that this power supply doesn’t have: two +12 V rails (it only has one), over current protection (OCP), and over power protection (OPP). It also fails to list a protection that the unit actually has, under voltage (UVP).