Articles: Cases/PSU
 

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Specifications

The PSU specs are up to today’s requirements: 99% of its full output power can be delivered across the +12V lines (there are eight of them here, each with a load capacity of 30 amperes).

The +3.3V and +5V rails have a load capacity of 25 amperes each, for a combined load up to 175 watts. This is going to be more than enough for any modern computer.

The PSU features 80+Gold certification which promises 87% efficiency at 20% and 100% load and 90% efficiency at 50% load.

UPS Compatibility

Working with my APC SmartUPS SC 620, the HCP-1200 was stable at loads up to 406 and 330 watts when powered by the mains and UPS batteries, respectively. The pair switched to the UPS’s batteries normally. When the mentioned load was exceeded, the UPS indicated overload but did not shut down immediately.

Output Voltage Stability

The +12V and +5V voltages are quite stable, always remaining within 3% from their nominal values. They are not going to deflect by more than 2% in a real-life computer.

The +3.3V rail is somewhat worse. When there’s a normal load on the +3.3V rail and a high load on the +12V rail, this voltage can fluctuate as much as 4%.

Output Voltage Ripple

The output voltage ripple is close to the permissible maximum of 50 millivolts on the +5V and +3.3V rails. The ripple is not that strong on the more important +12V rail although the permissible maximum is higher there (up to 120 millivolts).

Temperature and Noise

The HCP-1200 is cooled by a single 80mm fan.

It is a 9AH0812P4G131 model from Sanyo Denki. It’s got seven blades with rounded-off ends. Sanyo Denki fans are generally quieter than average fans from other makers, but the resulting acoustic comfort is going to depend on speed. Even a very good fan can't be silent when rotating too fast.

The fan works at a very low speed until a load of 600 watts, the PSU being almost silent then. As the load increases further, the fan accelerates in a linear manner, being quiet at loads up to 700 watts, audible at 800 watts and downright noisy at higher loads. The maximum speed of 3600 RPM at full load is just unacceptable and also redundant (the difference between the incoming and outgoing air decreases towards higher loads, down to a mere 4°C at a load of 1200 watts).

The PSU is so noisy at near-maximum loads that even the wailing of graphics card coolers seems more agreeable to the ear.

Efficiency and Power Factor

The power factor is typical for active PFC.

The efficiency is quite high: 90.9%, 90% and 85.9% at loads of 20%, 50% and 100%, respectively. However, this PSU is 80+Gold certified which means it must be 87% efficient at full load. Hopefully, the difference is due to some measurement inaccuracies rather than to the PSU’s own fault, yet I do suspect there’s something wrong with the PSU because its efficiency should have increased in the 220V power grid I connected it to during my tests. Our testing equipment can’t be that inaccurate.

+5V Standby Source

Despite its high specified load capacity of 4 amperes, the standby sources copes with its job without any problems.

Summary

The Antec HCP-1200 is a high-wattage and high-efficiency PSU which is almost silent at loads up to 50%. However, it is too noisy at near-maximum loads and I also have doubts about its compliance with the 80+Gold requirements in terms of efficiency.

 
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