A Closer Look

The Cooler Master iGreen 600W power supply comes with a shiny Titanium-look finish and uses a single 120mm fan on the bottom for cooling.  The fan speed is automatically controlled by the internal component temperature (speeds up as the combined load and temperature increases).  The power supply incorporates universal input (automatically adjusts to the AC line voltage) and active PFC that adds to the units green environmental friendliness. 

 

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An open honey-comb grill on the back allows the warm exhaust air to exit the power supply.  The small LED status indicator just above the On-Off rocker switch turns red if the power supply ever goes into a fault state (like a short circuit) and shuts down.

 

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The iGreen 600W power supply supports both ATX12V v2.2 and EPS12V V2.91 standards and is rated for a combined output power of 600 watts continuous, 700 watts maximum.    

 

Specifications (from the Cooler Master website)

 

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Cooler Master uses a double forward switching circuit design in their iGreen series of power supplies.  This really isn’t anything new but is a more efficient (and slightly more costly) way of building the front end circuit.

 

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Tripple +12V outputs

 

The Cooler Master iGreen 600W PSU provides three 12V outputs (+12V1, +12V2, and +12V3).  The following table shows the maximum and continuous rated current and what connectors are supplied by each output.  This appears to be a very good distribution across the +12V rails.

 

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Note: The maximum continuous load for all three +12V outputs is 456 watts.

 

Most typical users have little idea about the true power requirements of their particular system.   It might come as a surprise that the majority of modern PC’s actually use less than 200 watts of power (75% efficiency x 200 watts AC in = approximately 150 watts DC load).   For example: I used a WattsUp? Pro power meter to measure the AC power consumption during idle, CPU load, and gaming conditions of a modest PC consisting of the following components.

 

  • Epox EP-9NPA nForce4 Ultra motherboard
  • Athlon 64 3200+ (90nm) CPU
  • (2) Corsair 512 MB XMS 3200XL low latency RAM (2-2-2-5)
  • Leadtek GF6600GT PCI-e 128 MB video card
  • Western Digital 120MB Serial ATA HDD
  • Sony 16X DVD DDU1612
  • Panasonic DVD/CD Writer DVR-108 dual layer
  • FDD and Universal card reader
  • (2) 120mm low-speed cooling fans

 

System idle (sitting at Windows XP desktop)        112 watts

CPU full load (Folding@Home)                            139 watts

Gaming benchmarks (3Dmark)                           158 watts

 

I also measured the current flow going to the motherboard thru the +3.3V, +5V, +12V main and +12V aux lines with a FLUKE ammeter.

 

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So why then you might ask, would we need a 600W power supply?  For one thing a power supply should ideally be rated for approximately twice the expected maximum load.  If your PC will use between 150~200 watts of DC power then the PSU should be rated for at least 350~400 watts.  This will allow the power supply to operate at around 50% of its rated capacity.

 

But if you are a gamer with one or more high-end video cards, then you will definitely need a high-quality, larger capacity power supply!  For example: BFG Tech recommends using a power supply that can deliver a minimum 26A +12V with their GeForce 7800/7900 video cards.  If you have two GeForce 7800/7900’s in SLI mode, then a minimum rating of 34A +12V is recommended.  That’s over 400 watts for just the two video cards.

 

In the past, the majority of PC enthusiasts didn’t worry too much about their power supply — generic was frequently good enough.  For the most part those days are gone.  To operate a modern gaming rig or workstation today requires more thought and a greater investment to insure reliable operation.

 

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