Overview

The efficiency of the ST40EF increases over the PowerStream as the power load goes up, starting at a ~4% advantage at ~200W and up to ~6% at ~450W



Keep in mind, that all measurements are Input, measured on the Power cord.

Having said this, it’s time for the final calculations:

For the Silverstone ST40-EF
Pout = Pin x efc.
Pout = 454 x 80%
Pout = 363W peak

For the Powerstream 520:
Pout = 483 x 75%
Pout = 362W peak

I assume Pout is even slightly higher, comparing both loads and efficiencies. 75% on the Modstream might be slightly positive. I’m still working on a static setup, for running MAX. tests on all rails, so there will be a follow-up on this.

Voltage rails

All measurements where done, during the seventh and final max load run using a Fluke multimeter, using the min/max function. The used measuring-points are: 12V1 – Drive connector 12V2 – ATX 12V connector 5V – Drive connector 3,3V – Mobo connector
5VSB – Mobo connector



Having seen these rock solid values, I decided to do some more testing.

The Final Test

Opteron 185 @ 3Ghz stock V

DFI CFX3200-DR

Team Special CE5 @231 2-3-2-7

Sapphire X1900XTX

NEC 3540

Samsung 1648 DVD

Maxtor Max21 320Gb

4x 12cm Noiseblocker SX2

Though this isn’t the heaviest rig you can imagine, it’s quite representable as an upper mainstream gaming rig. I’ve thrown almost all games, benchmarks and test-utils at it, and it didn’t blink even once. Keep in mind it’s ONLY a 400W supply, so adding a dual Raid0, as I normally have, isn’t advisable, it’s more than capable of running any rig, varying from a nice home-entertainment system to a bare gaming rig.

Conclusive thoughts

The Silverstone ST40EF can be had for ~€70/$80 which makes it an attractive deal for those people out there who don’t run two video cards overclocked and want a rock stable system without worrying about the power bill. The ST40EF proved to consume less power than higher rated power supply we had in our test labs and could power a high end (single vga) gaming system without flinching.

If you’re looking for an efficient power supply the ST40EF from Silverstone will make an excellent choice and it comes recommended.

Pricing at Froogle.com

Pricing at Froogle.de