When working with an APC SmartUPS SC 620 both PSUs had a max allowable load of 295W. They both switched to the batteries successfully.

The cross-load diagram of the 600W model looks like the one of the TOP-500P7 U12 (see above): the +12V and +5V voltages boast excellent stability, and the +3.3V voltage is just good.

The 700W model proves even better in this test: its +3.3V voltage almost never leaves the green zone. You can only find a few yellow spots in the diagram.

Alas, the rest of the tests didn’t go well for the PSUs. The 700W model would overheat at full load. It would produce a characteristic noxious smell, although sustained such load continuously without failure.

The output voltage ripple of the 600W model is close to the allowable limit at full load. The 700W model violates the limits: it has a pulsation with an amplitude of 65 millivolts on the +5V rail, the allowable maximum being 50 millivolts.

There was also low-frequency (100Hz) pulsation. It amounted to 50 millivolts on the +12V rail at full load. That’s quite a lot, although below the allowable maximum of 120 millivolts. Anyway, I think that a well-designed PSU should have no low-frequency pulsation of the output voltages at all.

Both PSUs employ Globe Fan S0802512HD fans of the standard form-factor of 80x80x25mm.

The fans are fastened to the PSU case through rubber pads to minimize vibrations. Talking about that, I should note that the vibration of the fan frame is not the only and even not the main source of noise unless you’ve got a defective fan. It is the noise of the air flow, the bearings and the impeller that is the most annoying usually.

The regulation of the fan speed is implemented identically in both PSUs, so I’ll discuss the senior model. This diagram applies to the TOP-600P7 FR as well, with an appropriate limitation in output power.

So, the fans start out at a speed of 1800-1900rpm and maintain this speed until a load of 400W. After that they accelerate quickly. As a result, the PSU is not quiet. Its two fans and high component density (the latter means a high aerodynamic resistance inside the PSU and an increased noise of the air flow that’s passing through it) contribute to this.

The PSU is not cool, either. As I wrote above, the 700W model would produce an annoying smell when under full load. You can see the reason now: the temperature of the air that’s passing through the PSU increases by 21°C. I guess the high component density is the problem again. The fans just cannot pump enough of air through the PSU. This is indicated by the fact that the temperature growth is not affected by the acceleration of the fans at loads over 400W.

Both PSUs are 74-75% efficient. This is not high by today’s standards, which may be another cause for the overheat. The power factor barely reached 0.7 because these PSUs have neither active nor passive power factor correction.

Like the above-discussed TOP-500P7 U12, these two PSUs - TOP-600P7 FR and TOP-700P7 FR – are mainstream, even bottom-mainstream, products. They are not quiet and are prone to overheat at high loads. Their dimensions are larger than the standard, the efficiency is low, and the output voltage ripple violates the limits prescribed by the standard. The superb stability of the output voltages is in fact the only good point of these products.

The U12 and FR series differ in the cooling system only. The former uses 120mm fans, and the latter uses 80mm fans in couples.