A Closer Look

The Zeus 750W power supply enclosure is painted matte black and uses a single 80mm exhaust fan on the front-side for cooling.  Previous Zeus models have the fan located on the back like most other generic PSUs.  Mounting the fan on the front of the power supply, deep inside the PC enclosure helps isolate the fan noise and reduces the overall sound output from the power supply.

 

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 the AC line voltage) and active PFC that adds to the units environmental friendliness. 

 

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The open grill on the back allows the exhaust air to exit the power supply with minimal resistance.  The LED indicator beside the On-Off rocker switch shows the status of the power supply during operation: Orange = standby mode, Green = Normal operation, and Red = Fault. 

 

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The Zeus 750W power supply supports ATX12V v2.2/EPS12V and is rated for a combined, continuous output power of 750 watts.  The PSU includes universal AC line input and active PFC. 

 

Specifications (from the SilverStone website)

 

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Quad +12V outputs

 

The Zeus ST75ZF PSU incorporates four 12V outputs (+12V1, +12V2, +12V3, and +12V4).  The following table shows the maximum rated current and what connectors are supplied by each output.

 

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Note: The maximum combined load for all four +12V outputs is 60A (720 watts).

 

CAUTION: SilverStone informed me that there was an initial batch of ST75ZF power supplies that shipped with a wiring error in the 6-pin EPS 12V to PCI-E adapter cable.  You would only encounter this if you needed to use the optional 3rd or 4th PCI-E connector.  There has been no problem with the two hard-wired PCI-E cables that the majority of users will use.

 

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When the PCI-E adapter cable is plugged into the 6-pin EPS 12V connector, yellow wires should go to yellow, black wires to black, and the two orange wires to blank holes (no pins).  On the connectors that were wired wrong, yellow goes to yellow, but orange goes to black.

 

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Correct Wiring

Incorrect Wiring

 

If you find you have one of the incorrectly wired adapters, contact SilverStone and they will send you a replacement adapter free of charge.

 

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 750W 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 enthusiast 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.

 

The Zeus 750W power supply has a full assortment of cables and connectors. The main wiring harnesses measure approximately 22′ long to the first connector and all of the main power cables and two PCI-E cables are covered with black plastic mesh sleeving. 

 

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  • Main power connector (24-pin/20-pin)
  • ATX 12V (4-pin) using adapter from EPS 12V 8-pin
  • EPS 12V (8-pin)
  • EPS 12V (6-pin)
  • (2) PCI Express (6-pin) hard-wired
  • (2) PCI Express (6-pin) using adapters
  • (6) Peripheral Optical/HDD (4-pin)
  • (2) Peripheral FDD (4-pin)
  • (4) Serial ATA (15-pin)

Here are a few pictures showing the layout and components inside the Zeus 750W power supply.  In addition to relocating the single 80mm fan to the front of the power supply enclosure, the ST75ZF now has two main printed circuit boards to accommodate all the industrial class components.

 

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