Be Quiet installed one of their own SilentWings USC 120mm fan inside the Straight Power E8 400W unit. It is a fluid dynamic bearing fan with a patented high airflow design, yet it is a different, less powerful fan than the one we found in the E8-CM 680W unit. The fan of the E8 400W PSU can only achieve a speed of 910RPM at maximum speed, which is unnaturally slow.
We were surprised to find out that the Straight Power E8 400W unit is based on the exact same platform as the Straight Power E8 CM 680W unit which we reviewed recently. Fortron Source (FSP) is the OEM of this power supply.
The filtering stage of the power supply is acceptable and once again identical to that of the larger E8-CM 680W model. There are four Y-type capacitors, two X-type capacitors, two ferrite coils and a surge suppressing MOV; almost the minimum which the ATX standard dictates.
The primary capacitor is made by Teapo and is rated at 420V/330μF. Most of the secondary side capacitors are made by Teapo but some CapXon solid state capacitors can be found throughout the unit.
The heatsinks of the power supply appear to be adequate. The bridge rectifier can be seen on its own dedicated heatsink.
In order to increase the unit’s efficiency, FSP installed a DC to DC daughterboard. This unit only generates a 12V line, the 5V and 3.3V lines are generated via DC to DC circuits, with the exception of the 5VSB line which has its own small transformer. The Straight Power E8 400W is probably the lowest output PSU with a DC to DC circuit installed.