OCZ Fatal1ty 700 W Power Supply Review

Secondary Analysis

Even though EliteXstream 1,000 W and Fatal1ty 700 W are based on the same printed circuit board, the +12 V rectification is done by different components. The 1,000 W model uses four power MOSFET transistors to make the +12 V rectification, while the reviewed uses Schottky rectifiers: four STPS30L60CT.

The maximum theoretical current each line can deliver is given by the formula I / (1 – D), where D is the duty cycle used and I is the maximum current supported by the rectifying diode. Just as an exercise, we can assume a typical duty cycle of 30%. Of course the maximum current (and thus power) this line can really deliver will depend on other components, especially the coil.

Each +12 V rectifier supports up to 30 A (15 A per internal diode at 130° C), so we have a maximum theoretical current of 86 A (15 A x 4 / 0.70), which corresponds to 1,029 W, showing that this unit is clearly overspec’ed.

The +5 V output is produced by two STPS30L45CT Schottky rectifiers, each one capable of handling up to 30 A (15 A per internal diode) at 135° C. This translates into a maximum theoretical current of 43 A or 214 W. These are the same rectifiers used by OCZ EliteXstream 1,000 W.

The +3.3 V output is produced by two STPS30L30CT Schottky rectifiers, each one capable of handling up to 30 A (15 A per internal diode) at 140° C. This translates into a maximum theoretical current of 43 A or 141 W. These are the same rectifiers used by OCZ EliteXstream 1,000 W.

On the secondary heatsink we also found the rectifier for the +5VSB (“standby power”) output, an SBL1060CT. This device can handle up to 10 A (5 A per internal diode). This explains the higher current limit this power supply has for its +5VSB output (4 A) compared to other products. This is the same device used by EliteXstream 1,000 W.

Another component found on the secondary heatsink is a voltage regulator integrated circuit for the -12 V output (LM7912). This device has a current limit of 1.5 A. The use of this integrated circuit explains why the -12 V output was so stable during our tests (usually manufacturers use cheaper solutions for the -12 V output, which results in a tremendous ripple on this output). Again, this component is also present on EliteXstream 1,000 W.

Figure 14: +12 V rectifiers.

Figure 15: Rectifiers for the +5VSB output, +3.3 V output (two), +5 V output (two) and the voltage regulator from the -12 V output.

The outputs are monitored by a PS232 integrated circuit, which supports the following protections: over current (OCP), under voltage (UVP) and over voltage (OVP). Any other protection that this unit may have is implemented outside this integrated circuit.

Talking about protections, notice how this power supply has two thermal sensors on the secondary heatsink. Usually this means that the product has over temperature protection (OTP), but there is no reference to this protection on OCZ’s website and since the montoring integrated circuit does not implement this protection we would need to analyze the circuit in more details to confirm this suspicion.

Figure 16: PS232S monitoring integrated circuit.

The electrolytic capacitors from the secondary are from Teapo, a Taiwanese company. It would be great if the manufacturer also used Japanese caps here.