Reviews - Silverstone Zeus ST75ZF 750W
Sample Provided by: SilverStone (By jonny on Wed, Jun-21-2006)

Page 1 -

     Today I have in my possession the Silverstone Zeus ST75ZF. It is one of the latest efforts to come out of Silverstone. Manufactured by Etasis, four 12V rails, OEM quad SLI support, quiet operation with a single 80MM cooling fan... it looks like fun.

     The box is huge....

     But opening the box reveals the power supply is well protected, as well as a second box.

     The second box contains additional power adapters, a heavy-duty power cord (heavier gage than a typical PC power cord,) some Zip-Ties and some mounting screws.

     The power supply is wrapped in a static bag while the cables are tied up with a "bread-tie" and wrapped in bubble wrap.

     Let's unwrap this sucker and take some pictures...

     While we have the cables all unwrapped, let's do a head count.

Type of connector: Zeus ST75ZF
ATX connector 20+4
2 x 2 12V connectors 0*
2 x 3 PCIe 2**
8-pin Xeon/EPS connector 1
6-pin Xeon/AUX connector 1
5.25" Drive connectors 6
3.5" Drive connectors 2
SATA Drive power connectors 4
Fan only connectors (thermostatically controlled 12V only) 0
* An 8-pin to 4-pin adapter is included that combines +12V1 and +12V2
** A Molex to PCIe and AUX to PCI-e adapter is included so PCIe cards can be put on 12V3

     The label doesn't show the rails in the typical "table" layout, but it tells us everything we need to know...

     So if I were to break this out into a standard table, it would look like this:

Silverstone Zeus
ST75ZF
+3.3V +5V +12V1 +12V2 +12V3 +12V4 -12V +5VSB
33A 24A 18A 18A 18A 18A 0.5A 3A
Max Combined Watts 180W 720W 6W 15W
750W

     Notice how the combined 12V rails actually make up 96% of the power supply's total capability.

     The box shows us a few more details about the power supply... like how it has lead-free paint...

     24dBA is pretty quiet. We'll see how quiet that sounds when put into practice.

     Also notice the depth: 180MM. For you American-type peoples, that's 7". That makes it longer than your standard ATX power supply size, but it's also not "HUGE." A typical ATX PSU is 5.5" or 140MM deep. That would be something like an Ultra X-Finity 500W or OCZ GameXstream 600W (just off the top of my head.) Most PSU's are actually around 6" or between 150 and 155MM. To put the 180MM into perspective; a PC Power and Cooling 850W or 1kW Turbo Cool is 230MM deep.

     Going back to the rails... There are four 12V rails. Each is capable of 18A, but all four 12V rails is limited to 720W. This is more than enough power for most people and is actually more 12V power than I've seen on some 800W units!

The way the 12V rails are distributed are as follows:

  • 12V1: CPU-1. Typically powered through the 4-pin connector of a power supply. On the ST75ZF, power for CPU-1 is provided by the first two 12V wires on the 8-pin EPS+12V connector.
  • 12V2: CPU-2. Typically, dual CPU motherboards that would require each CPU have it's own 12V rail would get it's power from the second two 12V wires on the 8-pin connector. Silverstone also puts the SATA connectors on this rail.
  • 12V3: This rail powers many things. The AUX 6-pin is on this rail, as is all of the Molex connectors (used for hard drives, floppy and optical drives, fans, lights, etc.) and the main ATX connectors (powers fan headers and slot powered cards that require 12V.)
  • 12V4: This rail is dedicated for use with the PCI-e connectors.

     If your motherboard has only a four-pin connector for CPU power, Silverstone provides an 8-pin to 4-pin adapter. This puts your CPU on both 12V1 and 12V2, essentially splitting the load of the CPU between the two rails. Of course, this means upwards of 36A is available just for the CPU. Totally overkill. If you have room on your motherboard (no obstruction from components like capacitors) I would suggest just plugging the 8-pin power connector into the 4-pin receptacle leaving the extra 4-pins hanging off the edge of the connector. This will leave the CPU on 12V1 and eliminate the extra 6" of cable added by the adapter.

     The ST75ZF has both PCI-e connectors on 12V4. Other power supplies on the market with four 12V rails might put each PCI-e on it's own 12V rail (12V3 and 12V4) with as much as 20A available per GPU. Correct me if I'm wrong, but 18A is more than enough for almost ANY two video cards run in SLI or Crossfire. So there's certainly no foreseeable problem with hooking this power supply up the way it is and going balls out SLI or Crossfire. In fact, 18A dedicated for use with two PCI-e connectors is considerably more than what you would get with any dual 12V rail power supply on the market.

     I then contemplated quad SLI on the ST75ZF. nVidia suggests 11A per card, with half of that going through the 6-pin connector and the other half going through the PCI-e slot. Knowing that, I think we can still conclude that 18A is enough for four GPU's.

     But OEM quad-SLI cards use two power connectors each. Silverstone supplies us with two more adapters. One adapter converts two Molexes to one PCI-e and the other adapter converts the 6-pin AUX to a 6-pin PCI-e. The issue I have with this is that this puts more load on a rail that already has half of the GPU load on it already, goodness knows how many hard drives, maybe a TEC or a pump, your fans, etc.

     I doubt anyone reading this would have any problem with quad-SLI on the ST75ZF, but I think I'd rather take my SATA's off of 12V2 and onto 12V3 using Molex power connectors instead of the 15-pin SATA power connectors, take the CPU off of 12V2 by only using the first four pins of the EPS and then fabricating my own adapter that puts the additional PCI-e connectors on 12V2.

But that's just me.

Now to the load tests....


 

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