SilverStone SX550 SFX PSU Review

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SilverStone continues to enrich its SFX PSU portfolio. One of the most recent additions is the SX550, a budget-oriented unit featuring Gold-class efficiency and fixed cables instead of modular ones. As you can tell, it's intended to bring prices down.

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Transient Response Tests

Advanced Transient Response Tests

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

Ιn these tests, we monitor the PSU's response in two different scenarios. First, a transient load (10 A at +12V, 5 A at 5V, 5 A at 3.3V and 0.5 A at 5VSB) is applied for 200 ms while the PSU works at 20 percent load. In the second scenario, the PSU is hit by the same transient load while operating at 50 percent load. In both tests, we use our 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 tests "Advanced Transient Response Tests," and they are designed to be very tough to master, especially for a PSU with a capacity of less than 500 W.  

Advanced Transient Response at 20 Percent

Swipe to scroll horizontally
VoltageBeforeAfterChangePass/Fail
12V11.981V11.609V3.10%Pass
5V5.059V4.936V2.43%Pass
3.3V3.342V3.192V4.49%Pass
5VSB4.983V4.940V0.86%Pass

Advanced Transient Response at 50 Percent

Swipe to scroll horizontally
VoltageBeforeAfterChangePass/Fail
12V11.935V11.543V3.28%Pass
5V5.013V4.893V2.39%Pass
3.3V3.303V3.155V4.48%Pass
5VSB4.934V4.879V1.11%Pass
Image 1 of 5

The +12V rail performs poorly in these tests and the same goes for 3.3V. Only the 5V and 5VSB rails achieve decent performance.

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

Transient Response At 20 Percent Load

Image 1 of 4

Transient Response At 50 Percent Load

Image 1 of 4

Turn-On Transient Tests

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

For the first measurement, we turn off the SX550, dial in the maximum current the 5VSB rail can output and switch the PSU on. In the second test, we dial the maximum load the +12V can handle and start the PSU while it's in standby mode. In the last test, while the SX550 is completely switched off (we cut the power or switch the PSU off by flipping its on/off switch), we dial in the maximum load the +12V rail can before switching the PSU 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 12 V is 13.2 V, and 5.5 V for 5 V).    

Image 1 of 3

The 5VSB slope is almost perfect. We don't have any complaints about the second test's results either (standby to full 12V). On the contrary, ripple is increased for a short period during the last test before the rail settles down to the nominal voltage level.

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Aris Mpitziopoulos
Aris Mpitziopoulos
Contributing Editor

Aris Mpitziopoulos is a contributing editor at Tom's Hardware, covering PSUs.

15 Comments Comment from the forums
  • turkey3_scratch
    It doesn't seem like Silverstone can get anything right these days. I don't see how they can't include a rubber grommet where the wires leave the cage. When people are bending those wires around the case, they can easily rub up against a sharp edge like that and cut through the insulation or even damage the wires and increase the resistance. For $95 this is a rip off, I think it should be priced at $75. It's pretty loud, too.

    Also, according to your thing the PS113 doesn't support OTP, even though this unit seems to. It also seems to support UVP. Doesn't quite make sense to me. http://www.tomshardware.com/reviews/power-supplies-101,4193-22.html
    Reply
  • Aris_Mp
    Most supervisor ICs don't support OTP, so this protection is implemented through other circuits in PSUs that actually have OTP.
    Reply
  • Clamyboy74
    Having few cables is the point of an sfx psu. Sfx cases don't have much driver space, and short wires are good for small cases. Who in their right mind would but an sfx psu for use in a mod tower case, especially with a $95 price tag? When you review sfx psu's please bear into consideration that these are made for use in small cases, where short cables, few connectors are deal breakers for consumers. Thank you.
    Reply
  • turkey3_scratch
    The thing that hurts this unit is that there is no common hardware configuration that will fit into an SFX case and require more than a 400W power supply like the Corsair SF which is much better. Most high-end AMD GPUs like the R9 390 are just way too large to even fit into an SFX case. If you think of cards that can actually fit into an SFX case, they are going to be small form factor cards, which are almost always under 200W, or these days even quite less. CPU overclocking to extremes can't be done in SFX cases with limited cooler sizes and due to airflow restrictions, so, really, I don't see a position in the market where this unit can be competitive over the Corsair SF400. And since this unit does not come with an SFX to ATX bracket, it is implied that nobody will probably install it into a case that takes an ATX PS2 power supply.
    Reply
  • AlistairAB
    I have the corsaif sf450 and can confirm it blows the silverstone out of the water (silverstone never fixed their fan problems with their sfx psus)
    Reply
  • Samer1970
    18459920 said:
    The thing that hurts this unit is that there is no common hardware configuration that will fit into an SFX case and require more than a 400W power supply like the Corsair SF which is much better. Most high-end AMD GPUs like the R9 390 are just way too large to even fit into an SFX case. If you think of cards that can actually fit into an SFX case, they are going to be small form factor cards, which are almost always under 200W, or these days even quite less. CPU overclocking to extremes can't be done in SFX cases with limited cooler sizes and due to airflow restrictions, so, really, I don't see a position in the market where this unit can be competitive over the Corsair SF400. And since this unit does not come with an SFX to ATX bracket, it is implied that nobody will probably install it into a case that takes an ATX PS2 power supply.

    how about Titan X Pascal cards / 1080 ti? They consume 435Watt total System power.
    Reply
  • turkey3_scratch
    Not quite samer and not cards that would fit in an SFX case.

    Also, my bad guys, I meant SF450 not 400.
    Reply
  • Samer1970
    18460559 said:
    Not quite samer and not cards that would fit in an SFX case.

    Also, my bad guys, I meant SF450 not 400.

    maybe you should check the following cases :

    http://www.fractal-design.com/home/product/cases/node-series/node-202

    http://www.silverstonetek.com/product.php?pid=533

    http://www.silverstonetek.com/raven/products/index.php?model=RVZ02

    https://www.ncases.com/

    https://www.dan-cases.com/
    Reply
  • turkey3_scratch
    If you own a 1080Ti why would you get a mediocre PSU like this anyway? Once again, it doesn't seem to have a purpose at all. Once power requirements get anywhere past 300W you probably have high-end hardware in which case a unit like this is a poor choice over the SF600.

    Budget power supplies over 500W really have no place in this world. People purchase budget power supplies over 500W for three reasons:

    1) They have high end hardware and underestimate the need for a quality PSU
    2) They are uninformed and think "more watts" is better.
    3) They overestimate their power requirements.

    I suppose you could argue if they have 225W of hardware a 550W unit like this is perfect in terms of efficiency. Okay, maybe so. But that depends on how much you value efficiency, I suppose.

    The unit still performs poorly compared to Corsair. It's true, Corsair SF dominate the SFX market with the best units.
    Reply
  • Samer1970
    18460649 said:
    If you own a 1080Ti why would you get a mediocre PSU like this anyway? Once again, it doesn't seem to have a purpose at all. Once power requirements get anywhere past 300W you probably have high-end hardware in which case a unit like this is a poor choice over the SF600.

    Budget power supplies over 500W really have no place in this world. People purchase budget power supplies over 500W for three reasons:

    1) They have high end hardware and underestimate the need for a quality PSU
    2) They are uninformed and think "more watts" is better.
    3) They overestimate their power requirements.

    I suppose you could argue if they have 225W of hardware a 550W unit like this is perfect in terms of efficiency. Okay, maybe so. But that depends on how much you value efficiency, I suppose.

    The unit still performs poorly compared to Corsair. It's true, Corsair SF dominate the SFX market with the best units.

    Does not need to be 1080 ti , any 250 watt GPU card ... from 390 , 390x to others .. there are people on budget and use such cards in compact systems .

    I just mentioned gtx 1080 ti as a modern example ..
    Reply