OCZ ModXStream Pro 500 W Power Supply Review

[nextpage title=”Introduction”]

ModXStream Pro is a power supply series from OCZ featuring a modular cabling system and a very attractive price tag, at this moment featuring 500 W, 600 W and 700 W models, with the manufacturer promising that these units can deliver their labeled wattage at 40° C. We’ve already reviewed the 600 W version and were quite impressed by its performance. Let’s see if the 500 W model is also a good pick.

This power supply is manufactured by Highpower.

Figure 1: OCZ ModXStream Pro 500 W power supply.

Figure 2: OCZ ModXStream Pro 500 W power supply.

OCZ ModXStream Pro 500 W is 6 ¼” (160 mm) deep, using a 135 mm fan on its bottom and featuring active PFC circuit, of course.

The modular cabling system present on the 500 W model has six connectors, two red for the video card cables and four black for the SATA and peripheral power cables. The main motherboard cable, one ATX12V cable and one EPS12V cable are permanently attached to the power supply. They all have a nylon protection that comes from inside the unit. All cables use 18 AWG wires, which is the minimum recommended, except the +3.3 V (orange) wires from the main motherboard cable, which are thicker (16 AWG). This is exactly the same configuration used on the 600 W model. The cables included are:

• Main motherboard cable with a 20/24-pin connector, 17 ¾” (45 cm) long (permanently attached to the power supply).
• One cable with one ATX12V connector, 18 1/8” (46 cm) long (permanently attached to the power supply).
• One cable with one EPS12V connector, 18 1/8” (46 cm) long (permanently attached to the power supply).
• One cable with one six-pin connector for video cards, 18 ½” (47 cm) long (modular cabling system).
• One cable with one six/eight-pin connector for video cards, 18 ½” (47 cm) long (modular cabling system).
• Two cables with three SATA power connectors each, 18 1/8” (46 cm) to the first connector, 5 7/8” (15 cm) between connectors (modular cabling system).
• Two cables with two standard peripheral power connectors and one floppy disk drive power connector each, 18 1/8” (46 cm) to the first connector, 5 7/8” (15 cm) between connectors.

This configuration is identical to the one used on the 600 W model and is very satisfactory for a 500 W product.

Figure 3: Cables.

Now let’s take an in-depth look inside this power supply.

[nextpage title=”A Look Inside The OCZ ModXStream Pro 500 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.

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. Here we could clearly see that internally the 500 W and the 600 W models are based on the same project. Let’s see what are the differences between them on the following pages.

Figure 4: Overall look.

Figure 5: Overall look.

Figure 6: 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 is flawless on this stage, with two Y capacitors and one X capacitor more than the minimum required, plus an X capacitor after the rectifying bridge.

Figure 7: Transient filtering stage (part 1).

Figure 8: Transient filtering stage (part 2).

In the next page we will have a more detailed discussion about the components used in the OCZ ModXStream Pro 500 W.

[nextpage title=”Primary Analysis”]

On this page we will take an in-depth look at the primary stage of OCZ ModXStream Pro 500 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses one GBU805 rectifying bridge, which supports up to 8 A at 100° C if a heatsink is used, which is the case. At 115 V this unit would be able to pull up to 920 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 736 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. The 600 W model uses a 10 A bridge here.

Figure 9: Rectifying bridge.

Two SPP20N60C3 power MOSFETs are used on the active PFC circuit, each one capable of delivering up to 20.7 A at 25° C or 13.1 A at 100° C in continuous mode (note the difference temperature makes) or up to 62.1 A at 25° C in pulse mode. These transistors present a maximum resistance of 190 mΩ when turned on, a characteristic called RDS(on). This number indicates the amount of power that is wasted, so the lower this number the better, as less power will be wasted thus increasing efficiency. The 600 W model uses the same transistors but with a bigger packaging (TO-247 vs. TO-220), which improves heat transfer.

Figure 10: Active PFC transistors and diode.

The electrolytic capacitor used to filter the output from the active PFC circuit is from CEC and labeled at 85° C.

The reviewed power supply uses another two SPP20N60C3 power MOSFETs on its switching section, installed on the traditional two-transistor forward configuration. The specs for these transistors were already published above. The 600 W model uses different transistors here, but similar specs.

Figure 11: Switching transistors.

The primary is controlled by the famous CM6800 PFC/PWM combo controller. The 600 W model we reviewed used a different chip (FAN4800), which is basically the same chip from a different vendor.

Figure 12: PFC/PWM combo controller.

Now let’s take a look at the secondary of this power supply.

[nextpage title=”Secondary Analysis”]

This power supply has five Schottky rectifiers on its secondary, plus a diode in charge of the +5VSB output rectification.

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. Just as an exercise, we can assume a typical duty cycle of 30%.

The +12 V output is produced by two ESAD83-004 (“D83-004”) Schottky rectifiers connected in parallel, each one supporting up to 30 A (15 A per internal diode at 90° C, 0.55 V maximum voltage drop). This gives us a maximum theoretical current of 43 A or 514 W for the +12 V output. The 600 W model uses two rectifiers with double the current limit, so it has double the theoretical current/power limit from the 500 W model on this output.

The +5 V output is produced by one ESAD83-004 Schottky rectifier, which is capable of delivering up to 30 A (15 A per internal diode at 90° C, 0.55 V maximum voltage drop), giving us a maximum theoretical current of 21 A or 107 W for the +5 V output. The 600 W model uses two of this rectifier connected in parallel, so it has double the theoretical current/power limit on this output.

The +3.3 V output is produced by another two ESAD83-004 Schottky rectifiers, giving us a maximum theoretical current of 43 A or 141 W for the +3.3 V output. This is exactly the same configuration used on the 600 W model.

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: +12 V, +5 V and +3.3 V rectifiers.

The outputs are monitored by a PS224 integrated circuit, which supports over voltage (OVP), under voltage (UVP) and over current (OCP) protections, supporting two +12 V channels and also monitoring +5 V and +3.3 V outputs. This is the same component used on the 600 W model.

Figure 14: Monitoring integrated circuit.

All capacitors from the secondary are also from CEC.

[nextpage title=”Power Distribution”]

In Figure 15, you can see the power supply label containing all the power specs.

Figure 15: Power supply label.

This power supply has two +12 V rails (the monitoring integrated circuit really provides monitoring for two +12 V channels and we could clearly see the two current sensors – “shunts” – installed on the printed circuit board), distributed like this:

• +12V1: The cables that are permanently attached to the power supply.
• +12V2: The cables from the modular cabling system.

This distribution is perfect, as it put the CPU and the video card on separated rails.

Now let’s see if this power supply can really deliver 500 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 how the reviewed unit behaved 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 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.

The +12VA and +12VB inputs listed below are the two +12 V independent inputs from our load tester. During this test the +12VA input was connected to the power supply +12V1 and +12V2 rails, while the +12VB input was connected to the power supply +12V1 rail (EPS12V connector).

Input	Test 1	Test 2	Test 3	Test 4	Test 5
+12VA	4 A (48 W)	7.5 A (90 W)	11 A (132 W)	14 A (168 W)	17.5 A (210 W)
+12VB	3 A (36 W)	7 A (84 W)	10.5 A (126 W)	14 A (168 W)	17.5 A (210 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 (5 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)	1.5 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	104.0 W	203.2 W	304.9 W	398.4 W	498.8 W
% Max Load	20.8%	40.6%	61.0%	79.7%	99.8%
Room Temp.	44.5° C	44.2° C	44.7° C	47.6° C	44.8° C
PSU Temp.	45.2° C	45.3° C	46.2° C	49.1° C	48.8° C
Voltage Regulation	Pass	Pass	Pass	Pass	Pass
Ripple and Noise	Pass	Pass	Pass	Pass	Pass
AC Power	127.7 W	240.2 W	359.7 W	476.7 W	606.7 W
Efficiency	81.0%	85.0%	85.0%	84.0%	82.0%
AC Voltage	115.6 V	114.7 V	113.6 V	112.2 V	110.6 V
Power Factor	0.951	0.968	0.982	0.984	0.990
Final Result	Pass	Pass	Pass	Pass	Pass

OCZ ModXStream Pro 500 W can really deliver its labeled power, however during test five it shut down twice. Interesting enough this was exactly the same behavior we’ve seen with the 600 W model.

We were happy to see that the 500 W model has the same highlights from the 600 W model.

Since it has “only” the standard 80 Plus certification, we were expecting to see a unit with 80-82% efficiency across the board, but we are happy to be wrong: OCZ ModXStream Pro 500 W could achieve a high efficiency between 81% and 85% during our tests. These results are almost enough for this unit to get the 80 Plus Bronze certification.

Voltage regulation was outstanding, with all positive voltages within 3% from their nominal values – i.e., values closer to their “face value” than required, as the ATX12V specification allows voltages to be within 5% from their nominal values (10% for -12 V).

And then we have noise and ripple, which were below the maximum allowed, although we’d like to see lower numbers on the +12 V outputs (these results were once again compatible to what we saw on the 600 W version). Below you can see the results during test five. The maximum allowed is 120 mV on +12 V and 50 mV on +5 V and +3.3 V. All these numbers are peak-to-peak figures.

Figure 16: +12VA input from load tester at 498.8 W (80.4 mV).

Figure 17: +12VB input from load tester at 498.8 W (77.2 mV).

Figure 18: +5 V rail with power supply delivering 498.8 W (28.4 mV).

Figure 19: +3.3 V rail with power supply delivering 498.8 W (18.4 mV).

Let’s see now if we can pull more power from this unit.

[nextpage title=”Overload Tests”]

If we tried to pull more power with the unit still hot from our previous tests, the unit would shut down. So we waited until the unit was cold and then we immediately started to increase currents until we could find the maximum amount of power we could pull from it. The results you can see below. If we tried to pull one more amp the unit would shut down.

Input	Overload Test
+12VA	20 A (240 W)
+12VB	20 A (240 W)
+5V	8 A (40 W)
+3.3 V	8 A (26.4 W)
+5VSB	2.5 A (12.5 W)
-12 V	0.5 A (6 W)
Total	569.8 W
% Max Load	114.0%
Room Temp.	44.5° C
PSU Temp.	46.4° C
AC Power	694.0 W
Efficiency	82.0%

[nextpage title=”Main Specifications”]

OCZ ModXStream Pro 500 W power supply specs include:

• ATX12V 2.2
• EPS12V 2.91
• Nominal labeled power: 500 W at 40° C.
• Measured maximum power: 569.8 W at 44.5° C.
• Labeled efficiency: 86% at typical load (i.e., at 250 W), 80 Plus Standard certification
• Measured efficiency: Between 81.0% and 85.0% at 115 V (nominal, see complete results for actual voltage).
• Active PFC: Yes.
• Modular Cabling System: Yes, partial.
• Motherboard Power Connectors: One 20/24-pin connector, one ATX12V connector and one EPS12V connector (all permanently attached to the power supply).
• Video Card Power Connectors: One six-pin connector and one six/eight-pin connector in separated cables (modular cabling system).
• SATA Power Connectors: Six in two cables (modular cabling system).
• Peripheral Power Connectors: Four in two cables (modular cabling system).
• Floppy Disk Drive Power Connectors: Two in two cables.
• Protections: Over Voltage (OVP), Over Power (OPP) and Short-Circuit (SCP). Although not listed by the manufacturer, this unit also has Under Voltage (UVP) and Over Current (OCP) protections.
• Warranty: Three years
• Real Manufacturer: Highpower
• More Information: https://www.ocztechnology.com
• Average price in the US*: USD 65.00 (USD 40.00 after instant rebate).

* Researched at Newegg.com on the day we published this review.

[nextpage title=”Conclusions”]

OCZ ModXStream Pro 500 W is as good as the 600 W model we reviewed before, providing high efficiency (81%-85%), voltages very close to their nominal values (3% regulation against standard 5%), noise and ripple levels within proper range, ability to deliver its labeled power at high temperatures and protections up and running.

Internally both models are based on the same project, with the 600 W model having upgraded rectifiers for the +12 V and +5 V outputs. Externally, however, both models use the same cable configuration.

Then we have its price: only USD 40 at Newegg.com, making it a bargain and being a power supply with one of the best cost/benefit ratios on the market.