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[nextpage title=”Introduction”]

The new LSX series from Ultra so far features only two models, 650 W and 750 W, both with 80 Plus Bronze certification, single +12 V rail, synchronous design with DC-DC modules for the +5 V and +3.3 V outputs in its secondary, and lifetime warranty (if you register the product after buying it).

Models from the Ultra LSX series are manufactured by Andyson.

Ultra LSX 750 power supplyFigure 1: Ultra LSX 750 power supply

Ultra LSX 750 power supplyFigure 2: Ultra LSX 750 power supply

The Ultra LSX 750 is 6.5” (165 mm) deep, with a 135 mm dual ball bearing fan (Young Lin Tech DFS132512H).

The new Ultra LSX 750 doesn’t have a modular cabling system. All cables are protected with nylon sleeves. The power supply comes with the following cables:

  • Main motherboard cable with a 20/24-pin connector, 22” (56 cm) long
  • One cable with one EPS12V connector and one ATX12V connector, 22” (56 cm) long to the EPS12V connector, 5.9” (15 cm) between connectors
  • Two cables with two six/eight-pin connectors for video cards each, 22.4” (57 cm) to the first connector, 5.9” (15 cm) between connectors
  • Two cables with four SATA power connectors each, 18.5” (47 cm) to the first connector, 5.9” (15 cm) between connectors
  • One cable with three standard peripheral power connectors, 18.5” (47 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, 18.5” (47 cm) to the first connector, 5.9” (15 cm) between connectors

All wires are 18 AWG, which is the minimum recommended gauge.

Even though this power supply has four power connectors for video cards, allowing you to install two video cards that require two power connectors each without the need of adapters, they are available on two cables. The number of SATA power connectors is very good for a 750 W power supply (eight), even though we’d prefer to see three cables with three connectors on each cable instead of two cables with four connectors on each cable.

Ultra LSX 750 power supplyFigure 3: Cables

Let’s now take an in-depth look inside this power supply.

[nextpage title=”A Look Inside The Ultra LSX 750″]

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.

Ultra LSX 750 power supplyFigure 4: Top view

Ultra LSX 750 power supplyFigure 5: Front quarter view

Ultra LSX 750 power supplyFigure 6: Rear quarter view

Ultra LSX 750 power supplyFigure 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 Ultra LSX 750 has all required components, plus one extra X capacitor and two extra Y capacitors.

Ultra LSX 750 power supplyFigure 8: Transient filtering stage (part 1)

Ultra LSX 750 power supplyFigure 9: Transient filtering stage (part 2)

In the next page we will have a more detailed discussion about the components used in the Ultra LSX 750.

[nextpage title=”Primary Analysis”]

On this page we will take an in-depth look at the primary stage of the Ultra LSX 750 For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses one GBJ1506 rectifying bridge, which is attached to the same heatsink where the active PFC transistors are installed. This bridge supports up to 15 A at 100° C so, in theory, you would be able to pull up to 1,725 W from a 115 V power grid. Assuming 80% efficiency, the bridge would allow this unit to deliver up to 1,380 W without burning itself out. Of course, we are only talking about this component, and the real limit will depend on all the other components in this power supply.

Ultra LSX 750 power supplyFigure 10: Rectifying bridge

The active PFC circuit uses two SPW21N50C3 MOSFETs, which are capable of delivering up to 21 A at 25° C or up to 13.1 A at 100° C (note the difference temperature makes) in continuous mode, or up to 63 A in pulse mode at 25° C, each. These transistors present a 190 mΩ resistance when turned on, a characteristic called RDS(on). The lower this number the better, meaning that the transistors will waste less power and the power supply will achieve a higher efficiency.

Ultra LSX 750 power supplyFigure 11: Active PFC transistors

The electrolytic capacitor that filters the output of the active PFC circuit is from Teapo, and labeled at 85° C.

In the switching section, another two SPW21N50C3 MOSFET transistors are used, installed in the two-transistor forward configuration.

Ultra LSX 750 power supplyFigure 12: Switching transistors

The primary is controlled by the omnipresent CM6800 active PFC/PWM combo controller.

Ultra LSX 750 power supplyFigure 13: Active PFC/PWM combo controller

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

[nextpage title=”Secondary Analysis”]

This power supply uses a DC-DC project in its secondary, meaning that this unit is basically a +12 V power supply. The +5 V and +3.3 V outputs are produced by two smaller switching power supplies connected to the +12 V rail. The +12 V rail uses a synchronous design, meaning that instead of using diodes for its rectification it uses MOSFET transistors. Both designs (DC-DC and synchronous) are used to increase efficiency.

The +12 V output uses three IRFB3206 MOSFET transistors, two for the direct rectification and one for the “freewheeling” part of the rectification, each one capable of handling up to 210 A at 25° C or 150 A at 100° C in continuous mode, or up to 840 A at 25° C in pulse mode, with an RDS(on) of only 3 mΩ.

Ultra LSX 750 power supplyFigure 14: +12 V transistors

As explained, the +5 V and +3.3 V outputs are generated using two DC-DC converters, each one available as a small daughterboard attached to the main printed circuit board. Each converter is controlled by an APW7073 PWM controller and four ME75N03 MOSFET transistors, each one able to deliver up to 86 A at 25° C or up to 70 A at 70° C in continuous mode, or up to 20 A at 25° C in pulse mode, with a maximum RDS(on) of 9 mΩ.

Ultra LSX 750 power supplyFigure 15: One of the DC-DC converters

Ultra LSX 750 power supplyFigure 16: One of the DC-DC converters

The secondary is monitored by a PS113 integrated circuit, which only supports over voltage protection (OVP) and under voltage protection (UVP).

Ultra LSX 750 power supplyFigure 17: Monitoring circuit

All electrolytic capacitors used in this power supply are also from Teapo, and labeled at 105° C.

[nextpage title=”Power Distribution”]

In Figure 18, you can see the power supply label containing all the power specs.

Ultra LSX 750 power supplyFigure 18: Power supply label

Since this unit has a single +12 V rail, there is not much to talk about here.

Let’s now see if this power supply can really deliver 750 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 5 A (60 W) 11 A (132 W) 16 A (192 W) 22 A (264 W) 27 A (324 W)
+12VB 5 A (60 W) 10 A (120 W) 16 A (192 W) 21 A (252 W) 27 A (324 W)
+5V 2 A (10 W) 4 A (20 W) 6 A (30 W) 8 A (40 W) 10 A (50 W)
+3.3 V 2 A (6.6 W) 4 A (13.2 W) 6
A (19.8 W)
8 A (26.4 W) 10 A (33 W)
+5VSB 1 A (5 W) 1.5 A (7.5 W) 2 A (10 W) 2.5 A (12.5 W) 3 A (15 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 149.3 W 299.4 W 447.8 W 595.4 W 745.2 W
% Max Load 19.9% 39.9% 59.7% 79.4% 99.4%
Room Temp. 46.4° C 47.1° C 47.6° C 47.0° C 47.5° C
PSU Temp. 47.3° C 48.7° C 49.8° C 49.1° C 50.0° C
Voltage Regulation Pass Pass Pass Pass Pass
Ripple and Noise Failed at +5VSB Failed at +5VSB Failed at +5VSB Failed at +5VSB Failed at +5VSB
AC Power 181.1 W 347.6 W 519.2 W 699.0 W 889.0 W
Efficiency 82.4% 86.1% 86.2% 85.2% 83.8%
AC Voltage 112.5 V 111.3 V 109.4 V 106.3 V 105.3 V
Power Factor 0.972 0.989 0.994 0.996 0.997
Final Result Pass Pass Pass Pass Pass

The Ultra LSX 750 can really deliver its labeled wattage at high temperatures.

Efficiency was excellent, between 82.4% and 86.2%. This is great, because we are tired of seeing 80 Plus Bronze power supplies that can’t achieve 82% minimum at high temperatures, and the Ultra LSX 750 W can.

Voltage regulation was very good, with all voltages within 3% of their nominal values, except the -12 V output during all tests and the +5 V during test five (these outputs were still inside the proper range, though). 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 voltages closer to their nominal values than necessary most of the time.

Noise and ripple levels were always way below the maximum allowed on all outputs except on +5VSB, which was always way above the maximum allowed, between 260.4 mV in test one and 390.6 mV in test two. 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.

Ultra LSX 750 power supplyFigure 19: +12VA input from load tester during test five at 745.2 W (41.6 mV)

Ultra LSX 750 power supplyFigure 20: +12VB input from load tester during test five at 745.2 W (53.4 mV)

Ultra LSX 750 power supplyFigure 21: +5V rail during test five at 745.2 W (19.4 mV)

Ultra LSX 750 power supplyFigure 22: +3.3 V rail during test five at 745.2 W (23.2 mV)

Ultra LSX 750 Power SupplyFigure 23: +5VSB rail during test fiveat 745.2 W (390.6 mV)

Let’s see if we can pull even more from the Ultra LSX 750.

[nextpage title=”Overload Tests”]

Below you can see the maximum we could pull from this power supply. We couldn’t pull more than that because the power supply shut down, showing that its protections are working just fine. During this extreme overload condition, however, noise level was way above the maximum allowed on most outputs, at 278.2 mV on +12VA, 344.8 mV on +12VB, 320.2 mV at -12 V, and 463.4 mV at +5VSB. Noise level on +5 V (31.2 mV) and +3.3 V (32.3 mV) was still below the maximum allowed.

Input Overload Test
+12VA 31 A (372 W)
+12VB 31 A (372 W)
+5V 12 A (60 W)
+3.3 V 12 A (39.6 W)
+5VSB 3 A (15 W)
-12 V 0.5 A (6 W)
Total 849.2 W
% Max Load 113.2%
Room Temp. 47.1° C
PSU Temp. 52.0° C
AC Power 1,047 W
Efficiency 81.1%
AC Voltage 102.8 V
Power Factor 0.997

[nextpage title=”Main Specifications”]

The specs of the Ultra LSX 750 include:

  • Standards: NA
  • Nominal labeled power: 750 W
  • Measured maximum power: 849.2 W at 47.1° C ambient
  • Labeled efficiency: 85% at 50% load (375 W), 80 Plus Bronze certification
  • Measured efficiency: Between 82.4% and 86.1% at 115 V (nominal, see complete results for actual voltage)
  • Active PFC: Yes
  • Modular Cabling System: No
  • Motherboard Power Connectors: One 20/24-pin connector, one ATX12V connector, and one EPS12V connector
  • Video Card Power Connectors: Four six/eight-pin connectors on two cables
  • SATA Power Connectors: Eight on two cables
  • Peripheral Power Connectors: Six on two cables
  • Floppy Disk Drive Power Connectors: One
  • Protections (as listed by the manufacturer): Short-circuit (SCP)
  • Are the above protections really available? Yes, over voltage (OVP) and under voltage (UVP) available but not listed by the manufacturer
  • Warranty: Lifetime with registration, three years without registration
  • Real Manufacturer: Andyson
  • More Information: https://www.ultraproducts.com
  • Average Price in the US*: USD 110.00

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

[nextpage title=”Conclusions”]

The Ultra LSX 750 W comes with the right price for what it has to offer: very good efficiency between 82.4% and 86.1% at high temperatures, voltages closer than necessary to their nominal values, and low noise and ripple levels at the main outputs, and a satisfactory number of power connectors (four six/eight-pin connectors for video cards and eight SATA power connectors).

The only problem we saw with this unit was the high noise level at the +5VSB (a.k.a. standby) output, way above the maximum allowed.