SilverStone SX800-LTI PSU Review

Transient Response Tests

Advanced Transient Response Tests

For details on our transient response testing, please click here.

Ιn these tests, we monitor the SX800-LTI's response in several scenarios. First, a transient load (10A at +12V, 5A at 5V, 5A at 3.3V, and 0.5A at 5VSB) is applied for 200ms as the PSU works at 20 percent load. In the second scenario, it's hit by the same transient load while operating at 50 percent load.

In the next sets of tests, we increase the transient load on the major rails with a new configuration: 15A at +12V, 6A at 5V, 6A at 3.3V, and 0.5A at 5VSB. We also increase the load-changing repetition rate from 5 Hz (200ms) to 50 Hz (20ms). Again, this runs with the PSU operating at 20 and 50 percent load.

The last tests are even tougher. Although we keep the same loads, the load-changing repetition rate rises to 1 KHz (1ms).

In all of the tests, we use an oscilloscope to measure the voltage drops caused by the transient load. The voltages should remain within the ATX specification's regulation limits.

These tests are crucial because they simulate the transient loads a PSU is likely to handle (such as booting a RAID array or an instant 100 percent load of CPU/GPUs). We call these "Advanced Transient Response Tests," and they are designed to be very tough to master, especially for a PSU with a capacity of less than 500W.  

Advanced Transient Response at 20 Percent – 200ms

VoltageBeforeAfterChangePass/Fail
12V12.076V11.982V0.78%Pass
5V5.095V5.022V1.43%Pass
3.3V3.313V3.216V2.93%Pass
5VSB5.074V5.016V1.14%Pass

Advanced Transient Response at 20 Percent – 20ms

VoltageBeforeAfterChangePass/Fail
12V12.073V11.929V1.19%Pass
5V5.098V5.010V1.73%Pass
3.3V3.315V3.209V3.20%Pass
5VSB5.077V5.012V1.28%Pass

Advanced Transient Response at 20 Percent – 1ms

VoltageBeforeAfterChangePass/Fail
12V12.071V11.940V1.09%Pass
5V5.097V5.031V1.29%Pass
3.3V3.315V3.204V3.35%Pass
5VSB5.077V5.032V0.89%Pass

Advanced Transient Response at 50 Percent – 200ms

VoltageBeforeAfterChangePass/Fail
12V12.054V11.987V0.56%Pass
5V5.074V4.998V1.50%Pass
3.3V3.294V3.200V2.85%Pass
5VSB5.043V4.987V1.11%Pass

Advanced Transient Response at 50 Percent – 20ms

VoltageBeforeAfterChangePass/Fail
12V12.052V11.956V0.80%Pass
5V5.074V4.987V1.71%Pass
3.3V3.295V3.178V3.55%Pass
5VSB5.044V4.980V1.27%Pass

Advanced Transient Response at 50 Percent – 1ms

VoltageBeforeAfterChangePass/Fail
12V12.051V11.963V0.73%Pass
5V5.074V4.979V1.87%Pass
3.3V3.295V3.178V3.55%Pass
5VSB5.044V4.958V1.70%Pass

The+12V rail's transient response is pretty good. The same goes for the 5V and 5VSB rails.

Although the 3.3V rail demonstrates low deviation, its voltage does drop below 3.2V in two of our tests. With a little higher nominal voltage, this wouldn't be a problem.

Here are the oscilloscope screenshots we took during Advanced Transient Response Testing:

Transient Response At 20 Percent Load – 200ms

Transient Response At 20 Percent Load – 20ms

Transient Response At 20 Percent Load – 1ms

Transient Response At 50 Percent Load – 200ms

Transient Response At 50 Percent Load – 20ms

Transient Response At 50 Percent Load – 1ms

Turn-On Transient Tests

In the next set of tests, we measured the SX800-LTI's response in simpler transient load scenarios—during its power-on phase.

For our first measurement, we turned the SX800-LTI off, dialed in the maximum current the 5VSB rail could output, and switched the PSU back on. In the second test, we dialed the maximum load the +12V rail could handle and started the 800W supply while it was in standby mode. In the last test, while the PSU was completely switched off (we cut off the power or switched the PSU off), we dialed the maximum load the +12V rail could handle before switching it back on from the loader and restoring power. The ATX specification states that recorded spikes on all rails should not exceed 10 percent of their nominal values (+10 percent for 12V is 13.2V, and 5.5 V for 5V).

There is a tiny voltage overshoot at 5VSB. In the next two tests, we only find small waves, which are nothing to worry about.

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  • shrapnel_indie
    I know a guy that used to work for SLM at one time in his life. On one of the products for the company brands owned, he could mod it (it was a musical instrument amplifier) for just a couple of pennies and could have saved the company large sums of money on warranty work and improve reliability. He proposed the change, and it was denied because it broke the price-point, and warranties would cover any issues anyway.

    When bean-counters run the show, products will suffer, just so the price-point isn't exceeded and (now days particularly, immediate) profits are maximized. Makes me wonder if Silverstone listened to their bean-counters a little too much.
    0
  • Aris_Mp
    The thing I appreciate in SilverStone is that they didn't follow the marketing war in the warranty periods. For me it is really weird to see 10-12 years warranty in PSUs. Now with the mining craziness many companies are trying to find ways to get out of this.
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  • seanwilson5274
    why did an ad leading to this article popped up automatically on my windows 10 screen? I don't like being spammed, and even less so, when it comes in as sneaky as this.
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  • derekullo
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  • SilverStone Guy
    Anonymous said:
    When bean-counters run the show, products will suffer, just so the price-point isn't exceeded and (now days particularly, immediate) profits are maximized. Makes me wonder if Silverstone listened to their bean-counters a little too much.


    If bean-counters had their way, a PSU like this would have never been released in the first place! It's a very niche product that will not sell in significant quantities. Implementing sleeve bearing fan was not a cost-cutting move, it was out of necessity to keep the PSU noise low for the intended applications. At the time of development, FDB version of this fan was not yet available to us.
    0