LEPA B850W Power Supply Review

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Enermax have earned a solid reputation in the power supply sector over the years. They have been in operation now for over 20 years and have expanded their portfolio in recent years to accommodate enthusiast grade accessories. Their current power supply range is extensive and includes the excellent MODU82+ and Revolution 85+ series.

Unlike many other companies, Enermax are an OEM designer who create their own range of power supplies from the ground up, and have supplied quality designs for other well known companies such as Sapphire.

The LEPA range of power supplies is aimed by Enermax at the ‘mid range’ market (they don’t like the term ‘budget’), enthusiast users who are price sensitive and who want a competitively priced power supply without suffering too many compromises.

With a large 135mm fan, 80 Plus Bronze Certification and modular cabling, the LEPA B850W power supply appears strong on paper.

The design of this specific unit today has been outsourced to Sirfa Electronics (Sirtec), a name more well known in China than in Western Countries. Enermax are keen to point out however that quality control and R&D was still under control of the Enermax engineering team.

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  • 80 Plus Bronze Certified
  • Modular cables
  • Silent thermal controlled 135mm fan
  • 60 cm mainboard connector for comfortable cable routing
  • up to 6x (6+2) 8 pin PCI-E connectors
  • 10x SATA connectors
  • Multirail – up to four strong 12 volt rails
  • latest protection circuitry for high reliability and safety
  • SATA connectors with 3.3 V for upcoming SSD generation
  • Active PFC – power factor up to 0.99
  • 3 year warranty

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The LEPA B850 power supply ships in a rather bland looking box with a picture of the logo and product name along the bottom – an image of a Leopard is set to the side. The 80 Plus Bronze Certification logo is proudly displayed at the top left corner of the box.

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Inside, the power supply is shipped between a foam protective housing. A user manual rests on top of the power supply and the cabling is set to the right of the box.

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The bundle includes a region specific power plug, user manual, mounting screws and modular cables.

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lepa 850w cables LEPA B850W Power Supply Review

Cable Connectors – total
MB 20+4 pin x1
CPU 4+4 pin (8 pin) x2
PCI E 8 pin (6 pin +2) x6
Sata power connectors x10
Peripheral 4 pin (molex) x4
Floppy connector x1

The cables are all high quality sleeved, several of which are fixed into the body of the chassis. With six 8 pin PCI-E connectors, even the most demanding Crossfire or SLI configurations are fully supported.

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The LEPA B850 power supply is actually a rather attractive design, finished in plain black, with an orange section on the side indicating the product name and power output.

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A large 135mm fan takes centerstage at the top of the chassis, with the LEPA logo placed in the middle.

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The side of the power supply is fully vented to aid airflow and there is a power connector and switch placed to the side.

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LEPA B850 Power Supply
DC Output
+12V2 +12V3 +12V4
Max Output
20A 30A 30A
Total Power 180W 750W (62.5A) 9.6W 15W

The LEPA B850W power supply is capable of outputting 62.5A via the 12V output for a total of 750W of the 850W output.

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The LEPA product uses a 135mm Globe Fan which is rated at 12VDC 0.33A and has a plastic baffle. We have seen these being used before in other power supplies from companies such as OCZ.

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The power supply is a double forward design which utilises independently regulated topology. There are three large, black heatsinks spread across the PCB, to help with cooling. The overall build quality is good, with a clean layout and structure.

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We are pleased to see a quality 105c Rubycon capacitor rated at 400v, 470uF handling the primary. Secondary capacitors are supplied by Teapo.

Soldering is clean throughout and the input filtering initiates on the AC input receptacle with a traditionally designed X and Y capacitor configuration. Bridge rectifiers are connected to one of the heatsinks and the central heatsink is home to the main switching transistors. The cables are fully sleeved into the chassis and are held together with ties.

Additional technical assistance: Peter McFarland and Jeremy Price.

Correctly testing power supplies is a complex procedure and KitGuru have configured a test bench which can deliver up to a 2,000 watt DC load. Due to public requests we have changed our temperature settings recently – previously we rated with ambient temperatures at 25C, we have increased ambient temperatures by 10c (to 35c) in our environment to greater reflect warmer internal chassis conditions.

We use combinations of the following hardware:
• SunMoon SM-268
• CSI3710A Programmable DC load (+3.3V and +5V outputs)
• CSI3711A Programmable DC load (+12V1, +12V2, +12V3, and +12V4)
• Extech Power Analyzer
• Extech MultiMaster MM570 digital multimeter
• Extech digital sound level meter
• Digital oscilloscope (20M S/s with 12 Bit ADC)
• Variable Autotransformer, 1.4 KVA

12V output is combined for our testing.

DC Output Load Regulation


DC Load

0.20 -12.14
0.20 -12.12
0.30 -12.11
675W 11.32 3.30 12.35 5.01 47.47 11.89 2.00 4.97 0.50 -12.10
0.20 -12.10

The LEPA B850W delivered strong load regulation via +3.3V and +5V output. These are good results and the +3.3V and 5V rails remained firmly within +/-2% of the nominal voltage instead of the recommended +/-5%. There is slightly more fluctuation on the +12v output (0.38).

LEPA B850W Maximum Load

We managed to get the PSU to hit 904W before it would shut down. delivering around 54W more than the rated specifications.

Next we want to try Cross Loading. This basically means loads which are not balanced. If a PC for instance needs 500W on the +12V outputs but something like 30W via the combined 3.3V and +5V outputs then the voltage regulation can fluctuate badly.

Cross Load Testing +3.3V +5V +12V -12V +5VSB
760W 1.0 3.31 1.0 5.02 60.0 11.77 0.2 -12.02 0.50 5.00
165W 15.0 3.26 18.0 4.96 2.0 12.12 0.2 -12.04 0.50 4.97

The overall view is that the cross loading results are very healthy indeed. With +3.3V and +5V holding well within expected parameters. The +12V rail exhibited a little more variance, but it is still within safe parameters.

We then used an oscilloscope to measure AC ripple and noise present on the DC outputs. We set the oscilloscope time base to check for AC ripple at both high and low ends of the spectrum.

ATX12V V2.2 specification for DC output ripple and noise is defined in the ATX 12V power supply design guide.

ATX12V Ver 2.2 Noise/Ripple Tolerance
Ripple (mV p-p)

Obviously when measuring AC noise and ripple on the DC outputs the cleaner (less recorded) means we have a better end result. We measured this AC signal amplitude to see how closely the unit complied with the ATX standard.

AC Ripple (mV p-p)
DC Load +3.3V +5V +12V 5VSB
100W 5 5 25 5
225W 10 10 35 5
450W 10 10 50 10
675W 10 10 60 10
850W 15 10 75 10

Ripple results are extremely impressive across the +3.3V and +5V rails. The +12V is slightly less impressive, however it is still well within the rated tolerance guidelines. +12 V output peaked at around 75mV under full load.

Efficiency (%)
850W 82.70

For a 80 Plus Bronze specified unit, these results are very good, showing a maximum efficiency rating well over 86%. At maximum load this drops to just under 83%, which is again, a great result.

We take the issue of noise very seriously at KitGuru and this is why we have built a special home brew system as a reference point when we test noise levels of various components. Why do this? Well this means we can eliminate secondary noise pollution in the test room and concentrate on components we are testing. It also brings us slightly closer to industry standards, such as DIN 45635.

Today to test the power supply we have taken it into our acoustics room environment and have set our Digital Sound Level Noise Decibel Meter Style 2 one meter away from the unit. We have no other fans running so we can effectively measure just the noise from the unit itself.

As this can be a little confusing for people, here are various dBa ratings in with real world situations to help describe the various levels.

KitGuru noise guide
10dBA - Normal Breathing/Rustling Leaves
20-25dBA – Whisper
30dBA - High Quality Computer fan
40dBA - A Bubbling Brook, or a Refridgerator
50dBA - Normal Conversation
60dBA - Laughter
70dBA - Vacuum Cleaner or Hairdryer
80dBA - City Traffic or a Garbage Disposal
90dBA - Motorcycle or Lawnmower
100dBA - MP3 Player at maximum output
110dBA - Orchestra
120dBA - Front row rock concert/Jet Engine
130dBA - Threshold of Pain
140dBA - Military Jet takeoff/Gunshot (close range)
160dBA - Instant Perforation of eardrum

Noise (dBA)
850W 37.2

The power supply is fairly quiet until around 45% of total load and becomes audible, peaking at a rather noticeable 37 dBa at full load.

Temperature (c)

Exhaust temperatures are good in the lower end of the spectrum, rising to a 11c above ambient result at full load.

Maximum load

For those interested, we measured efficiency when stressing the unit to breaking point. Over 81% at 904W … hardly practical, but interesting regardless.

This is the first LEPA power supply we have reviewed and we are very impressed with the Enermax ‘budget’ range. There is no doubt in our minds that the LEPA B850W is a quality product, which not only achieves a very tight price point but is capable of a well rounded, stable power delivery.

We were initially impressed with the appearance because the plain black, well finished exterior will look great installed in a variety of systems. The modular cabling is nicely sleeved, indicative of high quality manufacturing and slots cleanly into the labelled connectors on the rear of the chassis.

Internally, the design is a double forward implementation which achieves 80 Plus Bronze rated specifications. It is certainly not a ground breaking new design from Sirtec, but it is stable, proven technology which works well.

Load regulation and cross load testing passed our tests, although +12V did exhibit a little fluctuation which slightly tainted a strong set of results. In a similar manner, the noise suppression was excellent and well within parameters, with both +3.3 V and +5V output peaking between 10 and 15mV. +12V was higher than we would have liked, peaking at 75mW, although again, it was still well within industry rated specifications.

Noise levels are a little higher than a few other designs we have reviewed in recent months, however in all practicality, no one will be driving this at close to full load daily. At 50% load, it is audible although never intrusive. If you are driving it at 700W+ however you may find the noise a little intrusive on a daily basis. It all depends on your particular noise concerns.

Overall, we are very impressed with the high output LEPA B850W power supply and pricing in the UK is very competitive. The product retails for £94.99 inc vat, which is an excellent asking price for an 850W, 80 Plus Bronze, Modular design.


  • Great appearance
  • modular
  • cabling is high quality
  • power delivery is excellent
  • competitive price
  • 80 Plus Bronze


  • +12V rail could be better
  • if loaded high can get noisy

Kitguru says: A well balanced power supply at a very reasonable price.

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LEPA B850W Power Supply Review, 5.0 out of 5 based on 1 rating
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  • Uriel

    Price is excellent, I agree. Dont need a PSU right now, but ive had good success with Enermax in the past.

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  • Gunther

    Enermax are normally mega expensive, so this is a wise move IMO. Dont like the ‘LEPA’ name though, its really not very good. obviously a play on ‘leopard’, but why? I dont get it.

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  • http://www.lowendia.com ET

    The PSU is described as modular, but I see no photo of where they connect. Also the table which shows cables vs. connectors looks to be unrelated to the modular cables, as it has 6 entries for 4 cables. So I have no idea what configurations of cables and connectors are possible, which I think is useful information.

    And what are the connectors on the non-modular cable?

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  • Gunther

    there is a shot of the connector ports on page 3..

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  • Jon

    They certainly hit a price sweet spot with this one. Excellent.

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  • http://www.lowendia.com ET

    Thanks, Gunther. Don’t know how I missed that. Lots of ports, that’s good.

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