The BitFenix Formula Gold 650W PSU Review: Balancedby E. Fylladitakis on June 13, 2018 8:00 AM EST
Hot Test Results
In the following tables we can see that the BitFenix Formula Gold 650W delivers fair power quality. The maximum voltage ripple on the 12V line is 34 mV, which may be an unimpressive figure nowadays but it is just 28% of the ATX design guide's recommended 120 mV limit. The filtration on the minor 3.3V/5V lines is a little worse, with the ripple reaching 22 mv (44% of the 50 mV ATX design guide recommended limit). On the contract, voltage regulation on the 3.3V/5V lines is at 0.5%, an exceptional figure, whereas the regulation of the 12V line reaches 1.4%. Keeping in mind the class of the product, these figures are excellent.
|Load (Watts)||131.08 W||326.57 W||487.81 W||647.02 W|
(20% to 100% load)
|Voltage Ripple (mV)|
|20% Load||50% Load||75% Load||100% Load||CL1
3.3V + 5V
Operation in high ambient temperatures affects the performance of the Formula Gold 650W PSU by a measurable, yet reasonable amount. The average nominal load range (20%-100%) efficiency drops by 0.8% regardless of the input voltage, going down to an average of 90.1% (230 VAC) / 88.2% (115 VAC). The efficiency drop is miniscule at lower loads but is more significant at high loads, suggesting that the components of the PSU are getting slightly thermally stressed under these conditions.
A look at our temperature graphs comes to back up our previous assumption, as the internal temperatures of the Formula Gold 650W PSU are quite high for a unit with this kind of power output. The thermal control does make an effort to keep the temperatures within reasonable levels, forcing the fan to spin a lot faster than before. Although the fan reaches uncomfortable noise levels with a load of just 300 Watts, it is unable to halt the ever-rising temperature. The Formula Gold 650W PSU barely works at maximum load under these conditions, as the temperatures are right before the point where its thermal protection would shutdown the unit.
Unlike operation in room temperature, the thermal control circuit will continuously increase the fan's speed under these conditions. The increase rate is almost linear, meaning that every increase on the unit's load will also increase the unit's noise output. The noise coming from the PSU's fan reached uncomfortable figures with a load of 300 Watts, with the sound pressure level going above 50 dB(A) at maximum load.