The SilverStone SX800-LTI SFX-L 800W PSU Review: Big PSU, Small Niche

Hot Test Results

The electrical performance of the SilverStone SX800-LTI is not greatly improved over that of the slightly older SilverStone SX700-LPT, but there is a small improvement on the output power quality. Voltage ripple figures are adequate, with our instruments recording a maximum of 36 mV, 40 mV and 32 mV on the 12V, 5V and 3.3V lines respectively. The paradox here is that the main 12V line seems to be much better filtered than the minor 5V/3.3V lines, which seem to have been somewhat neglected, perhaps because the designer just could not find enough space for more filtering components. Voltage regulation is good, with the 12V line maintaining a regulation of 2.2%. The 3.3V/5V lines are falling slightly behind, with the regulation at about 2.4%.

Although the SX800-LTI is rated for operation up to 40°C, the unit had little trouble operating inside our hotbox. Naturally, the energy conversion efficiency took a measurable hit and the average efficiency across the nominal load range dropped down to 91.6%. The reduction of the unit’s efficiency is somewhat greater at higher loads, suggesting that the active components are slightly stressed by the high ambient temperatures.

The internal temperatures of the SX800-LTI, while it was operating in our hotbox, were surprisingly low. PSUs usually reach temperatures exceeding 80°C under these operating conditions, but the SilverStone SX800-LTI hardly reached up to 75°C under maximum load. This time the cooling fan started even sooner, when a load just higher than 120 Watts. The thermal control of this unit is very aggressive, probably because SilverStone did not want to risk reducing its reliability over better acoustics performance.

Under these high temperature conditions, the cooling fan of the SX800-LTI not only starts sooner but also immediately increases its speed to audible levels. Inside the hot box, the PSU is louder with a load of just 200 Watts than with a load of 550 Watts in room temperature.  As the load increases, the speed of the fan constantly increases as well, reaching its maximum possible speed when the load exceeds 700 Watts. Thankfully our hotbox test is one of extremes and that - outside of poorly ventilated cabinets - few home users have environments this warm, as the sound pressure levels with a load above 500 Watts under these conditions would be practically intolerable for home users.